[Jonathan Caspell] This is a well-known doctor
that is beloved by the community,
by his friends.
[Gabriel Monte] This was shocking.
This is a straight-up, cold-blooded murder.
She had been pressuring him to marry her,
and he didn't want to have anything to do with that.
He started receiving nasty text messages.
He tells us that she has an ex-boyfriend,
and he was extremely jealous.
[Monte] He wanted revenge.
[Caspell] Is this real?
[Matt Powell] Every time the detectives went back and talked to her,
she had a different name.
Who is it?
Why was he targeted?
This was a gigantic whodunnit.
[narrator] Every day in North America,
dozens of people are murdered.
The key to solving the toughest of these homicides
lies in the final 24 hours of the victim's life.
To crack the case,
detectives must reconstruct that critical timeline,
the minutes and hours containing evidence
that can help unlock the mystery
and catch the killer.
Lubbock, Texas is a vibrant community,
uh, home to Texas Tech University,
and a very lively music scene,
where people from all over come
and just kind of experience Lubbock.
It's driven by its people,
uh, its tremendous people
that will do anything for you, uh, at any time.
And so, it's rare to have a violent crime.
That would all change in July of 2012,
when one of the more affluent parts of the city
becomes the backdrop of a very violent, shocking crime.
[phone ringing]
[narrator] The caller is a coworker of the victim.
When he hadn't shown up for work,
she got concerned
and she went over to the house.
[Monte] She finds blood on the floor of the house,
and she follows that blood trail to the garage,
where she finds a body.
The victim in the case is Dr. Joseph Sonnier.
[Monte] Dr. Sonnier lived on his own.
Uh, he was 57 years old
and the chief pathologist for Covenant Medical Center.
He is, uh, very well known in the medical community,
and is beloved by his friends.
[narrator] Police respond to Dr. Sonnier's home.
[Powell] Zach Johnson is assigned the case.
He's a 15-year veteran
of the Lubbock Police Department.
It's a normal working day for me,
and I'm on homicide call.
So, when control realizes that there is, in fact, a suspicious death,
we travel out to the scene.
A murder like this is unheard of,
and especially in this neighborhood.
I mean, this was shocking.
[Zach Johnson] At the scene,
Dr. Sonnier is laying face down on the garage floor.
There is blood surrounding his body.
There are several gunshot wounds
and stab wounds to his body,
and there is copious amounts of blood
which is now congealed on the floor of the garage.
[narrator] Investigators move inside the home
to begin processing this scene.
[Johnson] In the living room, we see eyeglasses on the floor.
There's a big bay window that is pushed in.
There's a chair that's been overturned.
There's a whiskey tumbler overturned,
and we find shell casings
on the floor of the living room.
There is multiple blood drops
that lead from the living room area directly into the garage.
And one thing we see in the living room
was a plastic bottle
that had had the end of it either cut out
or torn out, or something of that nature.
Uh, the plastic bottle raised some interest.
Uh, it appeared to have some type of gunshot residue
on one end of it.
What I immediately thought of was,
"This is a cheap man's silencer."
Somebody did not want anybody to know
that they had fired shots.
So, the question is, "What happened?"
The thing that immediately stands out to me
is that big bay window that's been pushed in,
and there is a footprint in the garden
outside of the home.
[narrator] Investigators posit a theory
of what likely transpired.
[Johnson] Somebody entered through that big window.
[Powell] Dr. Sonnier drops his drinking glass.
[Johnson] They fired several shots.
[Powell] And then, probably knocks over the chair
trying to get out of the situation.
Tried to run to safety,
in the meantime, drops his eyeglasses.
Well, I think it was Dr. Sonnier trying to escape.
[Johnson] The trail of blood that is leading from that area to the garage
would tell me, as an investigator,
"He's trying to get out of the house.
He's trying to get away from this shooter,
and he collapses inside the garage."
[narrator] Since Dr. Sonnier was still alive,
investigators surmise the killer followed him to the garage
and stabbed him to death.
What the medical examiner learned through the autopsy
was that Dr. Sonnier had been shot five separate times
and that he had been stabbed, uh, 11 times.
[narrator] To solve the crime, police need to piece together
the last 24 hours of Joseph Sonnier's life.
[Powell] Dr. Sonnier worked for Covenant Medical Center here in Lubbock.
So we start talking to coworkers.
[Monte] And they find out that Dr. Joseph Sonnier
arrives at Covenant Medical Center at 10:00 a.m.
[Powell] And he worked till about 7:00 at night.
And we also know from his, uh, from his security at home
that he arrived approximately 7:15 p.m.
[Johnson] Dr. Sonnier pours himself a drink in the living room...
...and gets murdered.
[narrator] And the next day, on July 11th,
his bloody body is discovered just before 2:00 p.m.
[Caspell] The medical examiner establishes the time of death
to be, uh, sometime the evening before,
7:15 p.m. to around 10:00 p.m.
[narrator] Police now have to determine
who is responsible and why they did it.
Dr. Sonnier's, uh, murder was a mystery.
It was a big whodunnit.
He was well-loved, well-liked.
So, you know, the news of his killing
was just shocking to a lot of people.
[Johnson] People in the neighborhood are pretty scared.
The last person they thought they would see murdered is Dr. Sonnier.
[narrator] Investigators ponder the motive.
[Powell] My first instinct, "It's a robbery.
It's a burglary. It's a burglary gone bad."
Uh, that's my first instinct.
[narrator] But when police look around the house,
they find nothing of value missing.
[Johnson] There's nothing disturbed in the house
other than our immediate crime scene.
The only thing that was stolen in that house
was Dr. Sonnier's life.
This is not a burglar gone wrong.
This is a straight-up, cold-blooded murder.
They wanted to be sure that Dr. Sonnier was killed.
[narrator] Police suspect the type of firearm used
may be a clue to the killer's identity.
We determine
that the casings came from a .25 caliber handgun.
Why are we using a very small caliber handgun
to commit a murder?
There's a whole bunch of larger caliber handguns
that will do the job with less ammunition.
[Michael Arntfield] A .25 caliber handgun
would be appealing to an offender
because they're easily concealed,
they're not particularly loud,
uh, and the recoil is minimal,
and they can control the weapon, uh, comparatively well.
[Johnson] And so, I have to consider a female perpetrator.
She can secret this gun inside a purse
and use it with a huge, uh, amount of surprise.
[narrator] But whether male or female,
who would want to kill Dr. Sonnier?
Investigators look into his family life,
which wasn't idyllic.
Dr. Sonnier was married for 26 years,
and the marriage ended in divorce.
[narrator] But that marriage also produced two sons,
who are now in their 20s.
When we talked to the sons,
they're beside themselves.
They're shocked.
They're in a state of disbelief.
They have no idea what has happened.
What made this tragedy, um, doubly, uh, bad
was that the sons of Dr. Sonnier
had lost their mom, uh, to a homicide,
almost two years to the day that they lost their dad.
Just something that you just never hear
and just never expect.
[narrator] Police wonder,
"Could their parents' murders be connected?"
[Powell] Certainly, that's something that you think.
Are the two murders linked in any form or fashion?
[Johnson] It's a very unique situation.
We've got two homicides
that occurred very close to each other
in the same family.
[narrator] Lubbock, Texas police suspect
there may be a connection between Dr. Sonnier's murder
and the slaying of his ex-wife two years earlier.
When it's learned that Dr. Sonnier's ex-wife
had been murdered in the past few years,
this clearly raises questions.
Is the same perpetrator involved?
Is there a link here between these two cases?
[Powell] So, when detectives started looking at the relationship
and the murder of Dr. Sonnier's ex-wife,
uh, they quickly learned that she had remarried
after divorcing, uh, Dr. Sonnier.
And her husband, at the time, shot her and actually took his own life.
[Johnson] It was a murder-suicide,
and so it was restricted to that particular relationship.
So that theory,
as far as those two cases maybe being linked,
was quickly dismissed.
[Johnson] So, why is our victim a victim?
Why did they end up dead?
[Powell] We're gonna delve very quickly into his personal life,
uh, to determine whether anybody has a motive
to harm Dr. Sonnier.
[narrator] His sons reveal that before he was murdered,
Dr. Sonnier was enjoying being single again.
[Monte] After Dr. Sonnier got divorced,
he started dating women,
and at the time that he was killed,
he was dating a woman
by the name of Richelle Shetina.
[narrator] Lead investigator Zach Johnson reaches out to Richelle,
who agrees to an interview at police headquarters.
[Powell] She's a divorcee and has four teenage sons.
Richelle Shetina and Dr. Joseph Sonnier met
at a local ballroom dancing studio
and hit it off.
[Johnson] So, they'd been dating about 10 months,
and as a 50th birthday present,
he says, "Hey, let's go off to Paris and celebrate your 50th."
And so, they had just come back from there.
Dr. Sonnier was the focus of Richelle's world.
[sobs]
Everything on social media is Dr. Sonnier and Richelle,
pictures and pictures and pictures
of their life together,
of their time in Paris and just being together.
So, when the detectives were questioning Richelle,
she was able to very quickly, to give, uh, her whereabouts,
to give a very detailed, uh, description of where she was
during the times of, uh, that were important to the detectives.
[Caspell] The day the murder happens,
Dr. Sonnier meets Richelle for lunch at 1:00 p.m.
and then returns to work.
[Johnson] After lunch, they went their separate ways,
and we know that Dr. Sonnier left
Covenant Medical Center
at around 7:00 in the evening.
[Powell] The Covenant Medical Center,
it was about a 4-minute drive from his home.
We know he got home around 7:15.
[cell phone chimes]
[Johnson] Richelle texts Dr. Sonnier
at approximately 10:32 p.m.
and doesn't get a reply from him.
So we kind of have the very beginnings
of a framework of time
where this murder occurred.
[narrator] Richelle's account confirms what medical examiners suspected.
Dr. Sonnier was likely killed on July 10th
between 7:15 and 10:30 p.m.
We push on with Richelle and with the interview,
and I just ask her...
And she brings up an ex-girlfriend,
uh, of Dr. Sonnier's.
Her name is Sharon,
and she's an emergency room nurse.
Dr. Sonnier had ended the relationship,
and that relationship didn't end well.
According to Richelle,
Sharon and Dr. Sonnier had dated a very short time,
and when Dr. Sonnier ended that relationship,
Sharon was very angry.
[narrator] Is it possible that Dr. Sonnier's ex-girlfriend Sharon
was enraged enough to kill him?
Police want to look closely at ex-partners, ex-lovers,
because jilted lover may seek vengeance,
and that can lead to violence.
[Johnson] I'm thinking, "We have a crime of passion."
This is a very cruel and brutal murder.
This person wanted to know that Dr. Sonnier was dead.
[Caspell] This is not random,
with this level of violence to it.
It is very important to investigators,
because it helps us to determine
the mindset of the killer
at the time of this murder.
[narrator] And investigators learn that Sharon had a hard time
taking no for an answer.
And during her relationship with Dr. Sonnier,
Sharon wanted to make it exclusive.
Dr. Sonnier didn't.
[Johnson] We discover that Sharon,
she's pressuring and pressuring him,
and he was like, "I don't want an exclusive relationship.
I want to end the relationship."
[Powell] Sharon got very spiteful
and sent some very vindictive, hateful text messages
to Dr. Sonnier.
You know, calling him a [bleep] ,
and, you know, "You're such a [bleep] "
[Johnson] She was not happy at all.
You know...
[Johnson reading]
Nasty text messages to Dr. Sonnier is alarming,
because it shows that there is unfinished business there.
[Johnson] But is that a reason enough to kill?
That's our question.
[narrator] Lubbock, Texas police catch up
with Dr. Sonnier's ex-girlfriend Sharon, a nurse,
to find out if she had anything to do with his murder.
Detectives learn that Sharon is in Austin
around the time of death of Dr. Sonnier.
[narrator] Austin is a 6-hour drive
from Dr. Sonnier's home in Lubbock.
So she was eliminated as a suspect.
[narrator] Back at Lubbock police headquarters,
Dr. Sonnier's most recent girlfriend, Richelle Shetina,
continues to cooperate with investigators.
[Johnson] And I ask her, "Is there anybody else that you know of
that would wanna harm Dr. Sonnier?"
She says, "Yes, uh, my ex-boyfriend."
[Powell] That was important information to us.
She has an ex-boyfriend,
uh, a guy named Mike Dixon
who's a doctor in Amarillo.
That's the first time detectives hear his name
as a potential person who may have an interest
in seeing Dr. Sonnier out of the way.
She tells us that Mike Dixon is not a very nice person,
uh, very hateful, uh, very vindictive,
very dishonest.
Dr. Dixon didn't take the breakup very well.
[narrator] A year-and-a-half earlier,
it had been love at first sight.
Mike Dixon, uh, and her first met
when she had gone to his clinic
for BOTOX injections.
She started dating him at that time.
[narrator] But Dr. Dixon was also married,
and despite promising for 18 months
to leave his wife,
he never does.
[Johnson] Richelle tells me, as this relationship goes on,
he really doesn't invest in her,
and she picks up on this pretty quickly,
and she took a lot of offense to, from Dr. Dixon.
And she finally said, "I'm done.
I'm through with this relationship."
[narrator] For Dr. Dixon, it goes from bad to worse.
His wife discovers the affair and leaves him.
[Monte] And then, Richelle Shetina did mention to investigators
that at some point, Dr. Dixon finds out
that she's dating another doctor in Lubbock.
[Powell] Mike Dixon did not take that very well.
He had even said that Richelle could continue to see Dr. Sonnier
if she would see him, too.
She is very much in love with Dr. Sonnier.
Richelle tells Dr. Dixon,
"I am not coming back to you, now or ever,"
and he is just livid.
[narrator] Richelle also mentions
that before Dr. Sonnier was murdered,
she suspected she was being stalked.
She remembers one morning at the gym very clearly.
[Powell] Richelle also tells us that one time,
uh, around the time of Dr. Sonnier's death,
they were in Dr. Sonnier's house
and they saw a flash from out on the back patio.
[narrator] At the time,
Richelle thought the camera flash may have been related
to her suspected parking lot stalker.
But now, she's not so sure.
[Powell] She tells us that she couldn't help but wonder
whether or not that situation with the flash
related, somehow, to the death of Dr. Sonnier.
[narrator] Was Dr. Dixon so obsessed with Richelle
that he spied on her and Dr. Sonnier?
Obsessive jealousy is really when we are just so fixated
on a previous partner,
it becomes all-consuming.
That's also a high-risk time
for a violent act or incident to occur.
[narrator] Is it possible Dr. Michael Dixon
killed Dr. Sonnier in a jealous rage?
[echoing gunshot]
To find out, Lubbock investigators drive two hours north
to Dr. Dixon's home in Amarillo to ask him in person.
[Johnson] So we go up to Amarillo
and we talk to Dr. Dixon.
And Dr. Dixon is very open about everything.
[narrator] Dr. Dixon admits he was cheating on his wife with Richelle.
[Johnson] He tells me that he was in love with Richelle,
that he was very sad that the relationship was over,
and that he had actually lost his marriage over that relationship
uh, when his wife discovered it.
He says the whole reason for the breakup with Richelle
was because she was pressuring him to get married.
She wasn't gonna mess with somebody
that wasn't gonna, you know, commit to her.
[narrator] Investigators ask Dr. Dixon point blank.
Did he murder Dr. Sonnier?
[Powell] Dr. Dixon tells detectives that he had nothing to do
with the murder that took place in Lubbock.
[Johnson] He's moved on from Richelle.
He's dating a medical student named Ashley.
He allows us to photograph him,
to check for defensive wounds,
to check him for any evidence of physical altercation.
Even provides us a DNA sample right there.
So he is being more than cooperative.
But inevitably, I ask him, "Can you account for your whereabouts?"
And Dr. Dixon tells me, "I was attending surgery in the morning.
I had lunch with Ashley and then I returned to work.
And then, in the evening, we had sushi at one of our favorite restaurants
and then, we came back to my place."
So, we immediately checked with Ashley
and we follow up on the alibi at the restaurant and it checks out.
We were even able to prove it through a credit card receipt.
So according to the timeline that we've corroborated
there was no way that Dr. Dixon was in Lubbock
to kill Dr. Sonnier.
[narrator] With Dr. Dixon ruled out,
investigators dig deeper into the victim's life
for suspects they may have overlooked.
Dr. Sonnier was very heartbroken after his divorce.
So he took some time.
He was able to get back into the dating game.
[Monte] Inside the living room of his home, they come across a notebook,
a little black book that Dr. Sonnier had
that listed some of the women he dated
and rated the women that he was dating.
That's kind of how he enjoyed being a bachelor was he dated women
and sort of had grades [chuckles] for them.
[narrator] It's Dr. Joseph Sonnier's last girlfriend Richelle
who now recalls someone else.
A woman reached out to Richelle directly
just months before Joseph was killed.
[Powell] In that letter, it also accused Dr. Sonnier of actually having sex
but never paid her for the first encounter that they had.
[Johnson] So here's another person
that is very angry with Dr. Sonnier,
but we have to ask ourselves, "Is this a motive for murder?"
[narrator] Police in Lubbock, Texas, follow up
on a poison pen letter from a woman named Tina.
Tina wrote that she was an online hookup
of murder victim Dr. Joseph Sonnier.
[Johnson] In the letter, this lady does in fact say
that Dr. Sonnier agreed to pay her for sex,
but she's very angry because Dr. Sonnier has not kept up
his end of the bargain.
[narrator] Tina was demanding that Dr. Sonnier pay up
and Dr. Sonnier's girlfriend at the time, Richelle, was furious about it.
Richelle confronts Dr. Sonnier about this letter
and Dr. Sonnier denies any knowledge of whoever this person is
or having a sexual encounter for money.
He said it was an extortion letter.
[Johnson] If Richelle is correct
and somebody is in fact out there
trying to destroy this relationship, who is it?
Where do we need to look?
There was no last name associated with Tina.
We knew that the letter was post marked in Lubbock,
but there was no return address.
We just didn't have a lot to go on.
So we start with Dr. Sonnier's family and friends.
"Hey, who is Tina? Have you ever heard of a Tina?
A Christina? Anybody of that nature?"
And they're like, "No, we've never heard of that person."
[narrator] Investigators are stumped,
but Richelle now tells police
that Tina is probably a fake name
and she claims to know who the real Tina may be.
She tells me that Trish was a former lover of Dr. Sonnier's.
[narrator] Police follow up with Dr. Sonnier's sons to confirm Richelle's story
and get more background on Trish.
[Powell] Trish had been Dr. Sonnier's dance instructor.
She ran a dance studio here in Lubbock
and the same dance studio where Dr. Sonnier ultimately met Richelle.
But Dr. Sonnier's sons told us that she did not have
a good relationship with the family.
They did not like the way that she treated Dr. Sonnier when they were in public.
[Johnson] Richelle tells me that after the relationship ended
at the request of Dr. Sonnier,
Trish becomes very angry with him.
But is that a reason enough to kill?
[narrator] To find out, police bring in Trish Berlanga for an interview.
[Johnson] Trish voluntarily arrives at the police station.
So we ask her, "Tell me about a letter from Tina.
Do you know anything about that?"
And Trish adamantly denies anything about that letter.
She didn't write it, she doesn't know anything about the letter from Tina.
"Okay, so tell us about your contacts with Dr. Sonnier.
We know that you call him and you text."
And she says, "I've barely spoken with him over the past ten months."
[narrator] But Richelle claims that Trish is lying.
[Powell] Trish wanted to get back together.
Uh, she didn't ever want the relationship to end.
Detectives obviously wanted to know
where she was at the time of Dr. Sonnier's death
and she tells us that she was in Florida.
[Johnson] We checked that alibi and it checks out.
She was in Florida,
so there was no way she was in Lubbock
to do the murder of Dr. Sonnier.
[narrator] Trish is now the third suspect to be eliminated
after Dr. Dixon
and the emergency room nurse Sharon.
And all had been accused by and acquainted with Dr. Sonnier's last girlfriend,
Richelle Shetina.
[Powell] It seemed like every time the detectives went back
and talked to Richelle, she had a different name.
From the outside looking in, we kind of thought
maybe she's a little too helpful.
Investigators often find it suspicious
when somebody appears too forthcoming,
offering multiple names
because perhaps this is a tactic
to divert suspicion from themselves.
[narrator] Police now wonder if Richelle has been hiding something all along.
[Johnson] And we find out that
in the days leading up to the murder,
Dr. Sonnier was actually texting friends to figure out
[reading]
[Powell] She had been pressuring him to marry her
and he didn't want to have anything to do with that.
[narrator] And that's counter to what Richelle believed and wanted.
[Johnson] After committing years of his life to a marriage,
he doesn't want to be exclusive with anybody.
[narrator] This revelation sheds new light
on the last lunch Richelle had with Dr. Sonnier
just hours before he was murdered.
So there was a possibility that when Dr. Sonnier
and Richelle Shetina had lunch that day
that he might have been breaking up with her.
[Johnson] And we find out the day that he was murdered,
he seemed very agitated.
And his coworkers asked, "Why are you so agitated?"
And he said, "I'm trying to end my relationship with Richelle.
I just don't know how to do it."
[narrator] And soon after, Dr. Sonnier is murdered.
[echoing thuds]
Officer Johnson calls Richelle back to the station.
For the first time, she finds out that Dr. Sonnier had planned to split with her
on the very day he was killed.
It's information that Richelle didn't anticipate.
[Johnson] She's not really been forthcoming
about the relationship,
and we know that Dr. Sonnier is slipping out of Richelle's grasp.
The relationship is starting to fade away.
So the big question is could she be trying to lead us off the path
that would lead to her being the murderer?
[echoing gunshots]
[narrator] One week after the murder
of prominent Dr. Joseph Sonnier,
police in Lubbock, Texas, now suspect his girlfriend, Richelle Shetina,
but Richelle strongly denies that she could ever harm the man she loved.
[Johnson] We were able to finally get Richelle's phone records
and everything that she told us
was corroborated by her phone records.
[narrator] With Richelle's alibi confirmed,
investigators hit another dead end.
[Powell] Everybody's getting a little frustrated at this point.
[narrator] But on July 17, a week after Dr. Sonnier's murder,
that frustration turns to hope when a man comes in with a shocking claim.
A man named Paul Reynolds who told them
that his friend confessed to him
that he had killed a doctor in Lubbock.
[narrator] Paul Reynolds is a nursing assistant and former Green Beret
living in Amarillo, Texas.
[Johnson] Paul Reynolds has been staying with his friend
and just within the past couple of weeks or so,
his friend is acting really, really strange
and it's enough to make Paul very nervous.
And he tells us his name is David Shepard.
[Monte] This could be a potential suspect.
[narrator] Paul Reynolds says he became friends with David Shepard
20 years earlier in the Green Berets.
But now he fears Shepard has gone off the deep end,
claiming to have killed Dr. Sonnier.
[Powell] Paul feels like it's necessary for him
to take immediate action from the things he's hearing.
[Johnson] Paul is concerned for his own welfare.
So he's got to stand up and stop it.
We find out that David Shepard is a 51-year-old,
unemployed salesman from Amarillo.
He's got three daughters, he was divorced.
But the question is why would an unemployed,
51-year-old divorced salesman...
Why would he want to kill a very successful doctor in Lubbock?
[Monte] David Shepard had gone bankrupt a couple of times.
He's financially troubled,
was doing all kinds of different things to try to make ends meet,
including having Paul Reynolds sleep on the couch, maybe pay a little rent.
The overriding theme is simple.
He can't hold down a job.
He's got three kids he's got to pay child support on.
So is money a motive here?
[narrator] But police first need to confirm
whether Paul Reynolds's statement is credible.
Or is he casting blame upon his friend
because Reynolds himself is involved in the murder?
There's one way to find out.
If an informer provides a number of details
that had never been released to the press or leaked to the press,
police know that there's some saliency to this informant's story.
[Johnson] Paul Reynolds tells us
that David Shepard had been stalking Sonnier for some time.
And Richelle said that there was somebody that she and Dr. Sonnier believed
to be in Sonnier's backyard taking pictures of them.
[narrator] Now investigators wonder if Richelle's description
of her stalker will match David Shepard.
[Powell] One of the things Richelle had told us
is that she had seen a very large man
that she felt was stalking her at her gym.
[Johnson] And Paul says, "Yeah, David is very large.
He's a large man."
[narrator] Paul then recounts David Shepard's alleged final trip to Lubbock
on July 10th, the day of the murder.
He left Amarillo and drove straight to Dr. Sonnier's home.
[Monte] Paul Reynolds told them that
David Shepard parks his car near Dr. Sonnier's house,
walks around to the backyard and lies in wait.
[gunshots]
[narrator] The pushed-in window and the plastic bottle are details of the crime
known only to police and to the killer.
Officer Johnson is more convinced
David Shepard is the likely shooter.
But one question remains.
So then we ask him, "Okay, why?"
And then, Paul tells us, "Well, David told me he was hired
by Dr. Mike Dixon to kill Dr. Sonnier."
[narrator] Mike Dixon was Richelle Shetina's ex-boyfriend.
[Johnson] It was a huge break in the case.
[Powell] Mike Dixon and David Shepard are good friends.
[narrator] Their relationship puzzles police.
How could such different people be such close friends?
[Caspell] One is a well-established plastic surgeon,
the other one is a drifter,
someone that's on the quick take.
And so, the relationship seems odd.
But it does really begin to have the hallmarks
of a true murder for hire plot.
[Johnson] So, after all the information that Paul told us,
we were certain that we had enough probably cause
to obtain an arrest warrant
for the arrest of David Shepard.
[narrator] On July 16th, 2012,
six days after Dr. Joseph Sonnier's homicide,
Lubbock police arrest 51-year-old David Shepard for murder.
Police secure a warrant to search Shepard's cellphone records
for communications with Dr. Dixon.
So we find out through David's cellphone records
that he'd been texting with Dr. Dixon
for several months and keeping Dr. Dixon apprised
of the stalking that David had been doing at Dr. Sonnier's house.
[Powell] And on David Shepard's phone
is a picture of the paned window
in Dr. Sonnier's backyard,
but on the glass, you see David Shepard
in the reflection on the window.
[Johnson] This picture places him right at the scene right
before the crime happens.
[narrator] Investigators now have all they need
to charge the mastermind of the murder,
Dr. Michael Dixon.
[Johnson] We arrest Dr. Thomas Michael Dixon
and charge him in connection with the murder of Dr. Joseph Sonnier.
[Powell] Dr. Dixon and David Shepard were both charged
with capital murder.
I made an offer to David Shepard's attorneys
that if he cooperated with law enforcement
and then ultimately testified against Mike Dixon
that we would waive the death penalty.
[narrator] David Shepard accepts their offer,
recounting key details of what led to the murder.
[Powell] David Shepard tells us that Mike Dixon
was obsessed with Richelle Shetina.
That he was very angry with her, wanted her back.
She's dumped him
and dating another highly successful doctor
and he... He wanted revenge.
[Johnson] So you had the perfect storm.
You had somebody desperate for money
and you had somebody willing to pony up to get revenge.
And then, he got some girl that was a stripper
in a bar there in Amarillo
to write this letter and sign it Tina.
So in the very beginning, they weren't about plotting a murder.
They were about driving a wedge
between Richelle and Dr. Sonnier,
but those ideas never pan out.
[Monte] So now this plan has escalated to murder.
[Johnson] Dr. Dixon provides him with a .25 caliber weapon
and David tells us that Dr. Dixon paid him
in three silver bars for the murder.
Dr. Dixon already advanced him one silver bar,
which he traded in for cash,
and then on the night of the murder, he provided him two more,
which he then went and pawned for cash money as well.
[narrator] Police confirm the sales of the silver bars at the pawn shop.
David Shepard's story checks out.
[Caspell] And so, we now have the pieces of the timeline
of the last 24 hours of Dr. Sonnier's life.
[Johnson] So, on July 9th, at 8:26 p.m.,
David Shepard sends a message to Dr. Dixon...
[reading]
Dr. Dixon replies...
[reading]
[Monte] The following day, Dr. Joseph Sonnier arrives
at Covenant Medical Center at 10 a.m.
[Powell] At about 1 o'clock, on the day of the murder,
Richelle and Dr. Sonnier had gone to lunch
and he had returned back to the hospital.
[Johnson] At 4:45 p.m., David Shepard arrives at Dr. Sonnier's house
goes to the backyard and lies in wait for Dr. Sonnier.
[Powell] Dr. Sonnier arrived at approximately 7:15 p.m.
At 7:44 p.m...
David sends Dr. Dixon a text.
[reading] Then all the messaging correspondence stops.
[Caspell] Inside the living room of his home,
Dr. Sonnier pours himself a drink
and looks out the back window of his home.
[Johnson] Dr. Sonnier looks outside through a back window
and sees David sitting there in his backyard.
[crashes]
[Caspell] David Shepard approaches the window, pushes it down,
raises his weapon and fires one time.
[gunshot]
[Johnson] David gets inside, shoots four more times,
and then, Dr. Sonnier stumbles into the garage
where David follows him as Dr. Sonnier collapses onto the floor.
David goes up to the body, removes an assassin's knife from his bag
and repeatedly stabs Dr. Sonnier.
Dr. Sonnier dies between 7:45 and 8:00 p.m.
And then, he leaves, drives to a lake and throws the murder weapon in a lake.
[Powell] He ultimately took detectives to that lake
and they were able to find that gun.
[Arntfield] It is able to be traced back to Dr. Dixon.
David Shepard pleads guilty to the murder
and is now serving life in prison.
[Powell] Mike Dixon was found guilty of capital murder of Dr. Sonnier
and was sentenced to life without parole.
This case is defined by obsession.
It's obsession with money,
it's obsession with love
and it's not being able to move on with your life