Produced by Susan Mallie and Jennifer Terker

[This story previously aired on August 17, 2019. It was updated on February 22, 2020.]

The North Carolina Court of Appeals ruled earlier this month on whether a father and daughter convicted of second-degree murder should get a new trial.

In August 2015, former FBI agent Tom Martens and his daughter Molly Corbett admitted killing her Irish-born husband Jason Corbett, insisting they beat him in self-defense with a brick paver and a baseball bat because Jason was choking Molly and threatening to kill her.

Prosecutors said Corbett's death was murder.

Now, Tracey Lynch is trying to set the record straight on her slain brother.

"They claimed it was self-defense," Lynch tells "48 Hours" correspondent Maureen Maher in her first American TV interview.

"The Martens didn't just murder Jason," Lynch says. "They tried to destroy his character."

"Jason was an amazing human being," Lynch says.

Jason Corbett was a 30-year-old father of two in Ireland, who suddenly found himself a widower when his first wife died of an asthma attack. He then decided he needed help with the children and hired Molly Martens, originally from Knoxville, Tenn. Soon, their relationship turned romantic, and they were married. Shortly after, they moved to the United States.

That's where the story turns leading up to the fateful night of August 2, 2015.

Tom Martens told a 911 dispatcher that his son-in-law got into fight with his daughter and he had to intervene. "He's bleeding all over, and I, I may have killed him," he said.

Molly also told police that Jason, then 39, was "screaming 'I'm going to kill you.'"

"I MAY HAVE KILLED HIM"

911 DISPATCHER: Davidson County 911… TOM MARTENS: My son in law, uh, got in a fight with my daughter. I intervened and he's in bad shape. We need help. 911 DISPATCHER: OK. What do you mean he's in bad shape? He's hurt? TOM MARTENS: He's bleeding all over and I - I may have killed him. TOM MARTENS: He's covered in blood 911 DISPATCHER: Alright, listen carefully. I'll tell you how to do chest compressions. I'll set a pace for you. … One, two, three, four.

The call came in the early morning hours of Aug. 2, 2015.

MOLLY CORBETT TO 911 [crying]: I — I'm certified. I just c — can't think. 911 DISPATCHER: OK, you have to stay calm. Let your training take over. We need — we need to try to do this to help him, OK? MOLLY CORBETT: OK.

Police arrived at the Winston-Salem, North Carolina, home to find Jason Corbett beaten to death and his blood on his wife Molly. They knew who did it: Molly and her father Tom Martens. The question was why?

TOM MARTENS [police interview]: He's got Molly by the throat like this.

Just hours later, Tom Martens, a 30-year FBI veteran, explains that he had been spending the night at his daughter's home. After being awakened by a commotion upstairs, he says he grabbed an aluminum Little League baseball bat he brought as a gift for the kids – and ran to her room.

TOM MARTENS [police interview]: He sees me coming and he goes around her throat like this [demonstrates a choke hold]. And I said, "Let her go." He turned and like, you know … "Let her go. I'm gonna kill her."

Martens says his protective instincts as a father instantly kicked in:

TOM MARTENS [police interview]: I hit him with the baseball bat. TOM MARTENS [police interview]: He reaches out and he grabs the bat and he's stronger than I am, and he pushes me down and I was scrambling on the floor. My glasses fall off. Now I'm thinking, "he's gonna kill me."

Molly Corbett told Davidson County Sheriff's investigators the same story:

MOLLY CORBETT [police interview]: He tried to hit my dad, I think, but he might have missed. And I, um, I hit him on the head.

She hit Jason with a paving stone that was sitting on her nightstand:

INVESTIGATOR WANDA THOMPSON: You have a brick on your nightstand? MOLLY CORBETT: Yeah. INVESTIGATOR WANDA THOMPSON: What was that — what was that for? MOLLY CORBETT: Um, the kids and I — we were going to paint — paint these bricks and flowers around the mailbox. TOM MARTENS [police interview]: I get the bat back. … I can't tell you how many times I hit him. … I can't tell you that. I mean, it was battle.

In Ireland, Jason's sister Tracy Lynch still cannot comprehend that he died this way.

Tracey Lynch: I just couldn't process it. It was — you know, he was my best friend. … We were just two of the closest people in the world to each other outside my husband and children.

Lynch and Jason were part of a big Irish family in Limerick. She remembers her brother as a kind and caring soul.

Tracey Lynch: We would just spend summers in Spanish Point in County Clare … hang out, fish. Just kinda normal traditional Irish upbringing, really.

Jason was Wayne Corbett's twin.

Wayne Corbett: We looked like each other but we were different in so many ways.

Maureen Maher: Would he have been the quiet one?

Wayne Corbett: No, no, no. Jason wouldn't have been quiet. You would hear him before you see him.

Jason married his first wife, Mags Fitzpatrick, when he was 27. They had two children, Jack and Sarah.

Tracey Lynch: They were just so happy and so excited with life and so enthusiastic about it as well. And — and they had Sarah, and you know, I remember them sayin' that they had, that their family was complete. They had their little prince and princess.

But in 2006, shortly after having their second child, Jason's storybook life came to an abrupt end, when Mags, a longtime asthmatic, suddenly had an attack.

Tracey Lynch: Mags woke Jason to say that she was feeling wheezy. And he sat her up. She started to take her nebulizer. And she started to get progressively worse. … We found out later, they called him in and told him that she had died in the ambulance on the way to the hospital.

Maureen Maher: And how old was he?

Tracey Lynch: He was 30.

Maureen Maher: So, 30 years old with a 2-year-old son.

Tracey Lynch: Yeah, and a 12-week-old daughter.

Jason Corbett became a widower with two young children at age 30. Tracey Lynch

With two very small children still at home, Jason Corbett had no choice but to pick up the pieces and move on after Mags died. A year-and-a-half later, 25-year-old Molly Martens answered an ad for an au pair. She arrived in Limerick in March 2008.

Lynn Shanahan: I met Molly the day she arrived in the airport in Shannon.

Lynn Shanahan is Jason's longtime friend.

Maureen Maher: And what was your impression of her when you met her?

Lynn Shanahan: My first thoughts and the first sentence to my own husband were, "This is not what Jason needs right now."

Maureen Maher: Why?

Lynn Shanahan: The minute I saw her with the big bouncing curls, she was in her 20s. She had a big bright color coat, fur collar, cowboy boots, was dressed and make-up done like a pageant queen as we would have said. She just seemed not the nannyin' type.

But Molly's uncle, Mike Earnest, says she was great with kids.

Mike Earnest: She grew up babysitting, always loved children.

Molly Corbett

Molly Martens had grown up in Knoxville, Tennessee. She had dropped out of Clemson University and was looking to begin a new chapter in her life.

Mike Earnest: I think, you know, she maybe was looking for something different, and that this might get her involved, too, in something that I think she was passionate about, which is children.

In Limerick, Molly instantly connected with Jason's children, 3-year-old Jack and 1-year-old Sarah.

Tracey Lynch: He liked her. She seemed gentle with the kids. … We started to see, you know, a little glimpse of the old Jason comin' back, that he was just, you know, not so sad all the time.

That's when Jason and Molly's relationship changed from professional to personal.

Lynn Shanahan: We went on holiday together. And the two of them looked very happy. The kids were happy.

They were soon making long-term plans.

It was at Freddy's Bistro in Limerick on Valentine's Day 2010, nearly two years after Molly Martens arrived to be an au pair, that Jason asked her to be his wife. Molly was over the moon and immediately began planning for a wedding back in the states.

Tracey Lynch: They came and — said that they got engaged, and we opened a bottle of champagne and toasted to their future.

Maureen Maher: Was he happy?

Tracey Lynch: He was happy, yeah, he was. He was in love. He loved Molly.

But that happiness wouldn't last for long.

A TROUBLED RELATIONSHIP

Molly Corbett and Tom Martens continue to give Davidson County investigators a blow-by-blow account of what they say happened that night in that bedroom. By now, they've washed off Jason's blood:

TOM MARTENS [police interview]: I tell you that guy was crazy. INVESTIGATOR WANDA THOMPSON: So, there's a history of domestic violence at the house? MOLLY CORBETT: Yes. INVESTIGATOR WANDA THOMPSON: How long has that been going on? MOLLY CORBETT: Forever. INVESTIGATOR WANDA THOMPSON: OK, you know your husband didn't survive his injuries, right? MOLLY CORBETT: I didn't think so.

Tom Martens claims that when he arrived earlier that evening to visit Molly and the kids, Jason was drunk. They all went to bed without incident. But hours later, Jason's daughter Sarah woke up from a nightmare.

MOLLY CORBETT [police interview]: She thought the fairies on her sheet were insects and spiders and lizards. … He was angry that he was woken up.

In the middle of her interview, Molly tells investigators she is in pain from the choke hold Jason had on her. They photograph her – including a red mark on the center of her neck. They also take pictures of Tom.

Investigators photographed Molly Corbett at the sheriff's office after Jason's murder. The prosecution later used this photo in court to show that Molly did not appear to have any injuries. Davidson County Courthouse

MOLLY CORBETT: Yeah, my throat hurts a lot. INVESTIGATOR WANDA THOMPSON: And how did you get that bruise? MOLLY CORBETT: Yeah, it was from the other night. INVESTIGATOR WANDA THOMPSON: Another night when? MOLLY CORBETT: Just when he grabbed my arm.

But as Molly and Tom tell tales about Jason's abuse, Jason's family had a different story. They say Molly was the one who caused problems in the relationship for years.

Tracey Lynch: The person in Ireland was very different to the one that we met … in Tennessee.

Jason's family supported the marriage. But when they arrived in the states for the wedding, they say they noticed Molly was behaving strangely.

Tracey Lynch: She was just very controlling. She was angry, I would say. And for someone who was about to get married, you know, she just wasn't herself. … She stayed in bed curled up in a ball. She didn't come out and socialize with anybody.

And that, Lynch says, wasn't the worst of it.

Tracey Lynch: What really set alarm bells ringing for me was when one of the bridesmaids told us before the wedding that Molly had told them that she had been friends with Mags, Jack and Sarah's mother, before she died of cancer. Mags didn't die of cancer, she died of an asthma attack.

And, of course, Molly never knew Mags. Jason's family was beginning to wonder if he was making a mistake by marrying Molly.

Paul Dillon: I said … "you're the most unhappiest man I've ever seen on his wedding day."

Jason's best friend and groomsman, Paul Dillon, thought he should walk away.

Paul Dillon: I asked him to just leave her and just get on a plane and go home. And he said he can't. He made the commitment.

One man believes the Corbetts had a reason to be concerned.

Keith Maginn: My name is Keith Maginn and Molly is my former fiancé.

Molly had been engaged to another man, who says they were still together when she left for Ireland to become Jason's au pair.

Keith Maginn: She had a lot of things going on. She had migraines. She had insomnia. … She basically— she spent a lot of time just soaking in the bathtub sometimes just crying on the bathroom floor.

Maginn claims both he and Molly struggled with mental health issues that he describes in a self-published book written before Jason died. He gave "48 Hours" no records to back that up, although Molly's medical records from years after her time with Maginn show that she was diagnosed with depression. Her brother Connor is reluctant to talk about it.

Maureen Maher: Much has been said about Molly's mental health … are you comfortable addressing that?

Connor Martens: I don't want to comment on that.

Jason and Molly Corbett, along with Jason's children, on their wedding day

At the time of the wedding, according to Molly's family, all was well, and she was happy to be walking down the aisle with Jason.

Mike Earnest | Molly's uncle: She looked very happy … and she looked like she was very happy to be getting married.

Jason was able to get a job transfer with the packaging company he had worked for in Ireland. He and Molly settled into the suburbs of Winston-Salem, where Molly got a job as a part-time swim instructor but spent most of her time with Jack and Sarah.

Tracey Lynch: I was concerned for Jason and his children. He had moved lock, stock and barrel from Ireland. Packed up his whole life, sold his house, gave up his job, and was on the cusp of a new life.

Mike Earnest: Well, my impression was that things seemed to be OK. I don't know if they seemed to be great. I did see occasions where … there seemed like there were issues coming up.

After four years, Molly was closer to the children than ever and considered them her own, but her relationship with Jason was in trouble.

Tracey Lynch: Jason started to talk about movin' home. He wasn't happy.

Maureen Maher: Did he say why he wasn't happy?

Tracey Lynch: Lot of it was down to the relationship with Molly. She was acting strange. Those things occurring that he wasn't comfortable with. … And he missed Ireland, wanted to move back. … But he knew and said that there would be huge difficulty in him coming back — once Molly found out.

Maureen Maher: And the kids at this point, they call her mom?

Tracey Lynch: Yes.

Maureen Maher: She is their mother.

Tracey Lynch: Yes.

Molly had always wanted to officially become Jack and Sarah's mother, but Jason would not allow it.

Maureen Maher: He didn't want to take the only mother they'd ever known away from them, but he wouldn't allow her to adopt them?

Tracey Lynch: Yes.

Maureen Maher: Why?

Tracey Lynch: Because of what she had said about Mags and because of her erratic behavior. … She waited until just before the wedding, and then all these stories came out. So when we spoke, he said, he just couldn't. How could he go ahead and allow Molly to adopt the children when he had all these issues of trust?

Now, with Jason dead, police ask Molly about his family. Jason's decision not to allow her to adopt Jack and Sarah hits hard:

MOLLY CORBETT: — and I'm scared they'll take the kids. INVESTIGATOR WANDA THOMPSON: Did you adopt the children? MOLLY CORBETT: No. INVESTIGATOR WANDA THOMPSON: Then that's a real possibility. MOLLY CORBETT [cries]: Oh, God.

The thought of losing the children is more than Molly can bear. But, investigators offer Molly a light at the end of a dark tunnel:

INVESTIGATOR WANDA THOMPSON [TO MOLLY]: At this point, after talking to your dad and talking to you, it looks like this is going to be self-defense. OK? I don't think there's going to be an issue with that.

SELF-DEFENSE OR MURDER?

Tracey Lynch says when she got the horrible news of Jason's death, she knew it could not have been self-defense as Molly and Tom claimed. She says, "Jason was a gentle person."

Tracey Lynch: I kept ringin' Molly. She wouldn't return my calls. Her parents, you know, no, they just completely stonewalled us. … I got 30 seconds on the phone with Jack … to tell him that I loved him and I was coming over to be with him.

Lynch says she was desperate to get to Jason's children as soon as possible.

Tracey Lynch: I was terrified.

Maureen Maher: What were you terrified about?

Tracey Lynch: I was terrified she would kill them.

Maureen Maher: You thought that Molly might kill the children?

Tracey Lynch: Absolutely.

Tracy Lynch told "48 Hours" she feared Molly would kill Jason's children. CBS News

Years before, Jason had named Lynch legal guardian if he were to die. And Tracey knew Molly would not give up the kids without a fight. Lynch immediately flew to North Carolina and filed for custody. And sure enough, Molly filed a motion for custody as well.

Lynn Shanahan: No one knew what scenario was playing in Molly's head, what she thought she needed to do. Or was there a chance that they would be in danger — if she knew they were taking them from her?

During the troubled marriage, Molly had asked an attorney what her rights to the children would be in the event of a divorce. She also secretly recorded arguments with Jason:

MOLLY CORBETT: Are you finished with your dinner, hon? JASON CORBETT: I'm talkin' to you! Is this how you treat … you just ignore me? I said, "I'd like to have dinner with my family" … I'm talkin' to you. I shouldn't have to say it over and over. I shouldn't have to say, "Molly — " MOLLY CORBETT [ignoring Jason]: Can you guys get out the stuff for pancakes? JASON CORBETT [yelling]: See! [slamming sound] There you go again. I'm talking to you and you're still going on talking about something else! SARAH CORBETT: Stop fighting!

A friend of Molly's spoke with her about Jason.

Maureen Maher: So, prior to his death, you never talked to her about their relationship?

Molly's friend: No.

Maureen Maher: And after his death, has she talked to you much about Jason and that relationship?

Molly's friend: Yes.

"48 Hours" agreed not to use the friend's name or show her face. She says she's been threatened by Jason's supporters.

Molly's friend: There were some signs that things weren't right.

Maureen Maher: Like what?

Molly's friend: Just you know controlling behavior. Some of the you know bad language and calling her names. … And then it just progressively got worse. … Forced sex … stuff like that.

Molly never reported any abuse to police.

Maureen Maher: Molly has said that Jason was verbally abusive, had started becoming physically abusive. … Do you think that any of that is possible?

Tracey Lynch: I don't believe any of that is true.

Four days after Jason died, both of his children were interviewed by a social worker:

SOCIAL WORKER: Tell me why you're here. JACK: Um, my dad died, and people are trying — my aunt and uncle from my dad's side are trying to take me away. To take me away from my mom.

Molly Corbett, center, with Jack and Sarah

Jack and Sarah are asked about the night their father died:

SARAH: My mom didn't want my dad to wake up because that would not have been a good thing. SOCIAL WORKER: Tell me why it's not a good thing. SARAH: Because he just gets really, really angry. He would be like, "why are you waking me up?"

Jack even explains the odd presence of the paving stone in the bedroom:

JACK: It was in my mom's room because it was raining earlier, and we were going to paint it we didn't want it getting it all wet.

When a social worker asks the kids about their parents relationship, both seem to support Molly's claims of abuse:

SOCIAL WORKER: Did you see him physically hurt her? JACK: Um, once or twice. SOCIAL WORKER: What did you see? JACK: Um, punching, hitting, pushing. SOCIAL WORKER: Has anybody told you what to say when other people talk to you? SARAH: My mom just said, "say the truth," you know. That's all she said.

But Lynch says that is not the truth.

Maureen Maher: You believe that Molly or someone in the Martens family coached the children?

Tracey Lynch: I'm certain of it.

The children were removed from Molly's care and placed with Lynch, who was staying at a hotel in North Carolina as the custody battle waged on.

Tom and Molly were allowed a visit., which was recorded on cellphone video. It would prove to be one of their last:

Tom Martens: Lots of people love you. Lots of people love you. Molly Corbett: There's lots and lots and lots of people praying for you. And for us. [Molly starts to cry, and Jack and Sarah hug her] Molly Corbett: I love you so much. Jack Corbett: I love you, too. Molly Corbett: I love you.

Sixteen days after Jason was beaten to death, Lynch prevails. Jack and Sarah would be heading back to Ireland with her and away from Molly, the only mother these children have ever really known.

Molly's friend: She was very, very devastated. She could barely function. I mean, she was absolutely distraught.

In the months following their return to Ireland, Lynch says that Molly repeatedly tried to contact Jack and Sarah, posting numerous messages on social media, hoping that somebody in Limerick would pass them on to the children.

Maureen Maher: Did you feel that Molly had any rights to them at all?

Tracey Lynch: No. Molly had murdered their father. And that's what I firmly believed at that point.

Lynch had a new battle on her hands: justice for Jason.

Tracey Lynch: After the autopsy … I recall the sheriff saying that, "It was blunt force trauma."

She was told that Jason suffered at least a dozen blows to the head.

Struck with the baseball bat and the brick, Jason Corbett suffered at least a dozen blows to the head. Davidson County Courthouse

Tracey Lynch: I looked at my brother in the coffin and witnessed just the devastation that one human can inflict on another.

After those first interviews, Molly and Tom heard nothing more from authorities. Despite Molly being told that the attack on Jason looked like self-defense, a murder investigation actually kicked into full gear. And in January 2016, five months after Jason died, father and daughter are shocked when they are charged with second-degree murder.

Mike Earnest: I mean, of course, they're devastated.

Tom Martens, the FBI veteran of 30 years, would now find out what it's like to sit at a criminal defense table.

Maureen Maher: They were both aware of the possibility that they might not walk out of that courtroom?

Mike Earnest: Correct.

A DAD & DAUGHTER ON TRIAL

Tracey Lynch: We were under a lotta pressure as a family, and you know, we were concerned. Were they going to be charged? So, it was a relief that the charges were brought.

Tracey Lynch felt sure from the beginning that Molly and Tom did not kill her brother Jason in self-defense. In fact, she believes she knows the real motive.

Tracey Lynch: There isn't a shadow of a doubt in my mind that Jason was beaten to death because he was going to leave with the kids.

Mart Molly Corbett and Tom Martens were charged with second-degree murder in the death of Molly's husband, Jason. Davidson County Courthouse

Lynch says Jason's plans to move back to Ireland with Jack and Sarah but without Molly had finally come together. And she and Lynn believe Molly found out that night.

Lynn Shanahan | Jason's longtime friend: I think Jason became surplus to her requirements. She didn't need him anymore. She just wanted the children.

After knowing her for years, Lynn Shanahan thinks Molly had been plotting to get the kids away from Jason for some time.

Lynn Shanahan: She was playing the long game that she was tellin' people that he had been abusive. She had her recordings. … She would have a case to get the children from him.

While awaiting the trial, Tracey Lynch settled Jack and Sarah into their new home back in Ireland. They had intensive therapy, she says, and adjusted well.

Nine months after returning to Limerick, Jack recanted what he'd told social workers after his father was killed:

SOCIAL WORKER [via Skype from N.C.] Is it true that your father was abusive? Or false? JACK: Um, false. SOCIAL WORKER: What did Molly say?

JACK: We were going to get interviewed. … She was saying a lot of stories, making up stories about my dad saying that he was abusive. And she started saying, "if you don't lie, I'll never ever see you again."

Jack says he only has one motive for telling the truth now:

JACK: I found what happened to my dad and I want justice to be served.

In 2019, Jack was 14 years old and Sarah was 12. While "48 Hours" visited Ireland, the children did not want to be interviewed, but the family did allow video to be taken of them.

Molly Corbett and Tom Martens went on trial together in July 2017. Family and friends of both the Corbetts and the Martens turned out in force.

Maureen Maher: What was it like to be so close, sitting by and — and in the same room with Molly and Tom?

Tracey Lynch: It was very — very difficult. … You're sittin' there and lookin' at, you know, two people … that had done something that was so malicious and insidious and ferocious.

Prosecutor Alan Martin: We thought we had evidence stacked up behind us a mile high.

Assistant District Attorney Alan Martin was confident the state would prove that Molly and Tom murdered Jason with malice.

Prosecutor Alan Martin: The viciousness and violence and excessiveness of the injuries that Jason suffered was really the cornerstone of our case.

Not only had the autopsy stated Jason suffered at least a dozen blows to the head, the exact number could not be determined, because he'd been struck repeatedly in the same spot.

Prosecutor Alan Martin: We looked at the damage to his scalp. His scalp was literally ripped from his skull. His skull was crushed.

For comparison, the jury was shown pictures of the defendants taken that same night.

Tracey Lynch: They didn't have a scratch, an abrasion. … Molly had a delicate bracelet on her that — that night that she continued to wear — throughout the trial.

Martin says that makes Molly and Tom's claim of self-defense a tough sell.

Prosecutor Alan Martin: You cannot be engaged in a donnybrook, like they described, with a man who is bigger than you, stronger than you, taller than you, and not have a mark on you. It's just not possible.

A blood spatter expert bolstered that argument.

Prosecutor Alan Martin: He can tell by looking at the spatter on the wall that Jason's head was 12 to 18 inches off the floor when some of the blows were struck.

Martin says that meant Tom was standing over Jason, still swinging, after Jason could no longer have been a threat.

Mike Earnest: I've known Tom Martins for 50 years. … This is not someone who loses control. This is not someone who is going to kill someone out of malice. … I absolutely do not believe there's any way Tom would hit him while he's down.

The defense pointed to photos that showed Molly did have that red mark on her neck. And a nurse practitioner testified that at a checkup just two weeks before he died, Jason said he'd been more stressed lately.

Mike Earnest: He had complained of getting angry for no apparent reason.

One strand of long, blonde hair was found in Jason's hand. It was likely Molly's but was never tested. And the autopsy indicated there were defensive wounds to Jason's left arm but not to his right – the one in which he supposedly held Molly.

Tom Martens prpeares to walk Molly down the aisle on her wedding day.

Still claiming he did what any father would do to protect his child, the defense's star witness, Tom Martens, takes the stand. No cameras were allowed but there is audio:

TOM MARTENS [testifying]: He said he was going to kill Molly. …I certainly felt he would kill me. I felt both of our lives were in danger. I did the best I could.

Molly did not testify and the defense was not allowed to offer evidence regarding Jason's alleged abuse.

TOM MARTENS [testifying]: I did not like some of Jason's behavior, particularly in regard to my daughter. That does not mean that I demonized the man.

Martens testifies he went only as far as he had to:

TOM MARTENS [testifying]: Once I got control of the bat, I hit him until I considered the threat to be over and when I considered the threat to be over, I quit hitting him. I considered the threat to be over when he went down.

During closing arguments, Alan Martin used the bat and paving stone from the Corbett bedroom to hit home his point at the prosecution table:

PROSECUTOR ALAN MARTIN: How much force [hits bat on table] does it take [hits bat on table] to split the flesh [hits bat on table] all the way to the skull? … You know what malice feels like when it comes from the brick that Molly had? It feels like, I hate him. I want those kids [hits table twice with the brick]. That's what malice feels like.

After nine days of testimony, arguments and graphic crime scene photos, the jury deliberated for just three hours.

Prosecutor Alan Martin: If they're coming back this fast with two unanimous verdicts, that's a really good sign.

Molly Corbett and Tom Martens were found guilty of second-degree murder

Tracey Lynch: It was just overwhelming relief really.

Jason Corbett Tracey Lynch

Prosecutor Alan Martin [in tears]: They beat him horribly and viciously. And no human being deserves to leave their marital bedroom with their skull destroyed like what happened to Jason.

Maureen Maher: Had you been thinking that it was possible that a guilty verdict might come back?

Connor Martens: I did not think it was possible that both of them would be convicted of second-degree murder.

Molly and Tom were immediately sentenced to 20-to-25 years in prison. That's when Molly turned around in court and said something to her mother.

Mike Earnest: "I'm so sorry. I should have just let him kill me."

As it turns out, this case may be far from over.

TRIAL AND ERROR?

After the verdicts, as Tom Martens and Molly Corbett were led off to prison, the jury foreman described his struggle.

Jury foreman: You saw tears. There were tears. I even had a few tears there while the verdicts were being ran through.

Jury foreman: It wasn't an easy decision. Somebody's life changes.

And then, he blurted out something that could potentially put those freshly-minted verdicts in jeopardy.

Jury foreman: We didn't discuss the verdict, but in having private conversations, everybody — we could read that everybody was going in the same direction.

Did the foreman just admit the jury discussed the case prior to deliberations? If so, that would be a direct violation of the judge's daily instructions to wait.

Prosecutor Alan Martin disagrees.

Prosecutor Alan Martin: It's been pounced upon as to say: aha, these people got together and started deliberating before they were supposed to. … What I hear is: we're a group of people who were sitting together seeing all these events transpire in the courtroom together. … Without talking about it, we can read each other's body language while we're in the courtroom.

But within days, the defense filed a motion to have the verdict thrown out based on jury misconduct. The trial judge denied that motion, but one year later, the defense went to the appellate court — this time arguing there were numerous errors at trial.

Mike Earnest: There's part of me that, you know, kind of maybe has some thankfulness that so many errors were made at trial that leaves room for a proper appellate decision in favor of Tom and Molly.

Markers indicate blood spatter on Tom Martens' boxer shorts. These spots were never tested, but the prosecution argues the spatter indicates that Tom was standing over Jason as he hit him with the baseball bat. Davidson County Courthouse

For one thing, there were blood stains on the hem of Tom's boxer shorts that the state said indicated he had been standing over Jason as he swung the bat. Those stains were assumed to be Jason's blood, but they were never tested.

Prosecutor Alan Martin: It's not practical, reasonable or feasible to test every single blood spot in every location.

Then there's the matter of the statements from Jack and Sarah. Molly's brother, Connor Martens, is upset that the trial judge did not allow them in.

Connor Martens: The kids' statement say that Jason was an abuser. And those interviews were conducted in professional environments on multiple occasions where Molly was not present.

Maureen Maher: And to the allegation from the Jason side of the family that they were coached by Molly?

Connor Martens: The interviews were conducted by professionals. And that's their job. … Why would the prosecution try so hard to prevent that from coming from trial? It's only evidence for the jury. Let them make that decision.

Jack's statement recanting what he'd said after he'd returned to Ireland was also never heard by the jury:

SOCIAL WORKER [via Skype from N.C.]: Is it true that your father was abusive? Or false? JACK: Um, false.

The Martens family has maintained all along it is that statement that was coached:

JACK [to social worker]: She was saying, making a lot of stories saying that my dad was abusive.

Maureen Maher: Do you think that the recanting should be allowed in too?

Connor Martens: I don't think so under the conditions. But if they can't, then the jury can discern which is truthful.

In January 2019, the state appeals court makes the rare move to allow oral arguments in Molly and Tom's case. Once again, both families flock to the courthouse with Lynch flying in from Limerick.

Tracey Lynch: There is always another step, or there is always something else to face.

Neither Tom nor Molly are present in the courtroom.

Maureen Maher: How does she feel her chances are with the appeal?

Molly's friend: I don't know. I think that she is cautiously optimistic. But I think that there's a lot of hopelessness, too. It's hard to trust the system after what they've gone through.

Each side has just a half hour to make its most important points. The defense goes first:

DEFENSE ATTORNEY: There are a number of statements from the children including, "dad got mad for no reason." … It was error to exclude them.

But the prosecution pushes back:

PROSECUTOR: The fact that somebody makes a statement doesn't mean it is trustworthy. … The children didn't want to go back to Ireland. …They had friends, they had schools. They were used to the USA. They rode horses. They lived in a nice house. They were comfortable.

The defense makes an impassioned argument about jury misconduct.

DEFENSE ATTORNEY: A juror is confessing on the courthouse steps not even an hour after the verdict that they engaged in private conversations.

Maureen Maher: Are you concerned about this appeal?

Lynn Shanahan: Well, I'm not concerned about it. … I think the case was really, really strong.

Mike Earnest says it is strength of a different kind that keeps Tom going.

Mike Earnest: Tom, I think, even as he sits in this atrocious miscarriage of justice knows that he saved his daughter's life. And, you know, I think he can sleep at night knowing that even if she is in prison, she's not dead.

Back in Ireland, Tracey Lynch waits for the appeals court's decision. She's written a book about this case and Jason.

Tracey Lynch: I wrote the book to give him back his character. The Martens, Molly Martens in particular, tried to destroy his character.

Tracey Lynch [reading from book]: "I smile briefly to myself as I realize that Jason eventually found himself back in the only place on this Earth he ever wanted to be — in the arms of his beloved Mags."

She finds comfort that her brother is buried in Limerick, next to his first wife and the mother of his children.

Jason Corbett is buried in Limerick, Ireland, next to Mags, his first wife and the mother of his children. Their wedding photo is on their shared headstone. CBS News

Tracey Lynch [at gravesite]: Jack and Sarah picked out the picture to change on the headstone from Mags to both of them. … I hope they're together somewhere.

Tracey Lynch: The memories just float to the surface, and you know, they'll always be part of our lives.

On February 4, 2020, the North Carolina Court of Appeals reversed Tom and Molly's convictions and ordered a new trial. They remain in prison.

A wrongful death lawsuit on behalf of Jason's children was settled by Tom Martens. There was no admission of wrongdoing by Tom or Molly.

Sarah Corbett Lynch, now 13, has written a children's book series on coping with loss.