How Texas mom became crucial witness in her OWN murder investigation - as journals and secret cell phone recordings revealed her despair over killer husband's affair

A young mother's final diary entry helped convince a jury she did not kill herself, but was actually murdered by her cheating husband.

Maria Munoz, 31, was heartbroken when husband Joel Pellot walked out of their Laredo home leaving her to take care of their two young sons.

He claimed she had overdosed on prescription pills when police found her dead in their home after he returned for a 'heart to heart'.

But the nurse anesthetist had injected her with toxic drugs stolen from the hospital where he worked in a bid to avoid an expensive divorce.

And Maria's diary and cellphone recordings helped investigators discover her husband's abuse, tracking her journey through grief to recovery and a renewed faith in the future.

'What is it that I want?' she wrote the day before she died, '#1 Move Forward!!'

Maria had met her husband when she was a young nurse in Puerto Rico and he was an ambitious medical student eleven years her senior.

They married in 2011 and made their home in the Texas border town where she gave up her career to support her husband.

But in 2020 Maria discovered her husband was cheating on her when she found an airline ticket for a European holiday he planned to take with a colleague from his hospital.

Matters came to a head on September 19, the Saturday before her death, when Maria saw his car outside the home of his lover Janet Arredondo.

Arredondo called police who in turn called Maria as she travelled home with her husband.

'Hey, I'm f***ing talking to you right now,' they heard Pellot tell her as she took the call, 'Hang up the f***ing phone.'

He had broken the windscreen with a punch before they arrived home, and she texted him the next morning to tell him she was hiring a lawyer.

'We can do this with minimal lawyer intervention. It's too much money,' he shot back.

Hours later there was a change of tone.

'I am so sad I am hurting inside,' he emailed her.

'I want to sit down with you to talk, w/o arguing. A heart to heart.'

Maria was nervous as she prepared for what would be their final meeting.

'I just ask if you can pray for me,' she messaged her friend Yazmin Martnez on the Monday, 'tonight we are going to talk.'

Police received another call in the early hours of Tuesday morning, this time from Pellot who told them his wife was not breathing and may have taken some prescription pills.

They found him dressed in surgical scrubs and performing CPR on his now dead wife as the couple's two young boys slept in the next bedroom.

Pellot went to a bathroom cabinet to get the prescription clonazepam he said she had overdosed on, but pocketed the bottle as police tried to resuscitate his wife.

'Yeah, she's been super depressed,' he told them.

Pellot was taken to the police station for interview where surveillance cameras caught him crying, screaming and pushing furniture around when left alone.

He admitted that syringes and intravenous equipment found in the house were his but they were part of his everyday work equipment.

Investigators were also curious about a puncture mark on Maria's arm but it was four months before toxicology results came through and they had little to go on.

In the meantime Pellot attended his wife's funeral where he wept over her coffin.

'What made me feel angry was him near the casket,' Martinez told CBS 48 Hours.

'Crying over her, giving her kisses. Like why now? You have made her suffer and cry so much and you're doing this now?'

But what detectives did have were Maria's journals.

'Life is so unfair,' she wrote in one entry, 'My husband the man I love so much is causing me so much pain.'

'I don't want to be sad anymore, I don't want my heart to hurt, I don't want my mind to be in torture,' she wrote in another.

And they spoke of a continued hope that her marriage could be saved.

'Lord this is a lot for me,' she wrote, 'All I really want to do is see change in him.'

Police also found cellphone video recordings Maria had made including one angry exchange in their car.

'What is it that you want me to do?' she asked Pellot at one point, 'what are the expectations you have on this marriage?

'You walk out that door, we're getting a divorce,' she warned him.

'Alright fine, you got it,' Pellot shot back, slamming the car door.

The medical examiner had found drugs in Maria's body but the diaries and recordings were enough for her to rule out suicide.

Pellot's boss at the hospital, anesthesiologist Dr John Huntsinger, was suspicious at the results and urged police to investigate further but it was four months before the toxicology report revealed there was no clonazepam in Maria's system.

Instead there were seven other drugs typically used during surgery, including Propofol which can only be administered by injection.

'I was very shocked to see Propofol, said Dr Huntsinger, 'Hers was the highest level I've seen.

'I believe this was death by Propofol.'

Arredondo had been interviewed by police and admitted that Pellot had routinely brought drugs, including Propofol, back from the hospital.

She also revealed that Pellot had admitted to injecting his wife on the night she died.

'He wanted to uh, just calm her down,' she told them, 'so he did it with medication.'

Pellot was arrested and claimed in court that he gave her Narcan, a drug used to reverse an opioid overdose.

'Someone tried to bring her back to life, and it wasn't the paramedics, it wasn't the police. It was Joel,' his attorney Roberto Balli told the court.

'So he did not want her dead. This was a terrible accident.'

But the jury took less than an hour to find Pellot guilty of his wife's murder and he was sentenced to life imprisonment in March this year.

Prosecutor Marisela Jacaman said the most important witness at trial was Maria herself through the journals which showed she had gotten over her husband.

'I've heard of emotional abuse, I've seen it, I've worked around it but I never realized how prevalent it is even in our lives where you can relate to some of the things that Maria was experiencing,' she explained.

'And she was a great mother, she was just an amazing person.

'And that energy? We felt it.'

'She loved him, and she adored him,' said Maria's friend Angela Montoya.

'She just loved him too much.'