Iowa son fights to prove his father did not kill his mother with a corn rake. "They got it wrong"

Trysten Mullis: We're at the farm that I grew up on. This is where … me and my brother and sister grew up … these big white buildings here are the hog barns.

Trysten Mullis, along with his younger siblings Taylor and Wyatt, and his parents Todd and Amy, lived on a 400-acre Iowa farm where they grew soybeans and corn and raised pigs.

Trysten Mullis (at the farm): It's a whole family effort to … run a farm this size.

Erin Moriarty: And what are you feeling when you like look out here and --

Trysten Mullis: Just nostalgia. … it's just kind of peaceful, you know?

That November morning in 2018, started off routinely. While his sister and brother stayed in the house, Trysten, then 13 years old, was with his parents preparing for a shipment of baby pigs.

Trysten showed me inside the hog barn where they were working.

Trysten Mullis (inside the hog barn): Now we're going into the main area of the hog barn. This is where your pigs would actually be in.

Trysten's job that morning was to carry heaters from the front of the barn to each pen. Todd was working on the water supply pipes. Amy was cleaning the lights.

Trysten Mullis (inside the hog barn): What she was doing is she would get on the bucket here and stand up, and she would unscrew it like that (demonstrates). … Drop it down, get off the bucket, clean it in a separate bucket, and then get back up here and screw them back in.

At one point, Trysten remembers noticing that his mom looked dizzy and unsteady.

Trysten Mullis: She was getting down kind of slow and really grabbing on to the gate … You could kind of see her loopy and swaying a little bit.

Just four days earlier Amy had had a minor medical procedure, and Trysten says he and his dad were concerned. This was her first day back on her feet.

Trysten Mullis: We knew something was not right.

Trysten says his mom agreed to go into the house and rest. But before she left, they asked if she could do one thing on her way: get a pet carrier out of the red shed. Trysten says they needed it later that day to protect some kittens from heavy machinery.

Trysten Mullis: We asked her if she could get it outside of the door.

Trysten Mullis: She walked down the side there.

Trysten Mullis: And walked out that door … The last time I saw her was through that window, right in the wall there (points to the front end of the barn).

Trysten says he and his dad continued working for about an hour-and-a-half before taking a break.

Trysten Mullis: We noticed that … the pet carrier wasn't outside. So he said, hey, can you go, uh, get the pet carrier out? … We just figured she couldn't get it.

Trysten went to the red shed to get the pet carrier, and that's when he found his mom on the ground with a corn rake in her back.

Trysten Mullis: I was just praying that she was still alive.

Trysten yelled for his dad, and they got Amy into the truck — calling 911 as they rushed to the hospital.

911 OPERATOR: Delaware County 911. What's the address of your emergency?

TODD MULLIS: I just grabbed her and threw her in the truck. My son's holding her.

911 OPERATOR: OK, you're headed to the hospital and she's in your vehicle?

Erin Moriarty: How did you hear that your mom didn't make it?

Trysten Mullis: Dad walked in the room and he had tears in his eyes … and told us that mom had passed away.

Amy's mother Peggy, her brother Jeff and her stepfather Randy are still coming to terms with what happened that day.

Jeff Fuller: She was my best friend … growing up … Amy was a very vibrant person. She had a big personality.

Randy Munson: She was always concerned about other people, about her family, about her children.

Trysten says that he and his father assumed his mother's death had been a horrible accident; that she had just fallen on the rake. But less than a year later, Todd was on trial for her murder.

Even though Todd and Trysten maintained that Amy's death was an accident, the state medical examiner, Dr. Kelly Kruse, said it was a homicide. She found a large bruise on the side of Amy's jaw and scrapes and bruises on Amy's knuckles — possible signs of a — noted that while Amy had six puncture wounds on her back, the corn rake only had four tines.

DR. KELLY KRUSE (testifying at trial): There were two different directions of the six puncture wounds. …

PROSECUTOR MAUREEN HUGHES: And what do those different directions indicate to you?

DR. KELLY KRUSE: To me they indicate that she would have to be impaled with the rake at least twice. … possibly three times.

Dr. Kruse determined that Amy's injuries had to have been caused by someone striking her with the rake. Iowa Division of Criminal Investigation special agent Jon Turbett, now retired, was called in to help local law enforcement.

Jon Turbett: I'm thinking at some point Todd and Amy end up in that red barn, and Todd attacks Amy … and … she's hit two or three times with a corn rake.

Jon Turbett: We learn that the marriage … is not … maybe what it would look like on the outside … There were things boiling underneath.

Amy was having an affair, and according to her brother Jeff, she wasn't happy and planned to leave Todd.

Jeff Fuller: Her words to me were, "Todd's gonna flip out."

Erin Moriarty: And what did that mean to you? What did flip out mean to you?

Jeff Fuller: To me, that meant that he would … not go quietly, he would not give up half of … his land … in a divorce.

Jon Turbett: And that becomes … a big part of his motive of killing Amy.

And according to her friend Patricia Christopherson, Amy was afraid of Todd.

PATRICIA CHRISTOPHERSON (testifying at trial): I asked her why she stayed and she said she was scared of Todd and if he found out about, um, wanting a divorce or an affair, that he would kill her.

Investigators say Google searches found on Todd's iPad show that not only did he think about killing his wife, he planned it in advance.

Jon Turbett: You see searches on … unfaithful wives … and killing cheating wives at different points in history.

According to prosecutors, Todd's plan was to send Amy to the red shed that morning and then ambush and kill her, But that wasn't all.

PROSECUTOR MAUREEN HUGHES (at trial): He sent his 13-year-old son to go and find his mother, who he had just slaughtered.

When Todd testified, he told the jury he never did those damning Google searches, that he did not know his wife was having an affair, and that he did not kill her.

DEFENSE ATTORNEY GERALD FEUERHELM (at trial): Todd … did you ambush your wife, Amy, in that shed that day and brutally beat her and chop — chop her up with that corn fork?

Since Trysten was the only other person working on the farm that day, his testimony was crucial. He initially told police that he had been with his dad all morning — essentially providing an alibi for his father. Trysten later added that he did leave his dad's side twice to get a drink of water and that he briefly lost sight of him. Because he was a minor, Trysten wasn't shown on camera.

PROSECUTOR (at trial): Do you know exactly how long your dad wasn't in your sight?

PROSECUTOR: … Trysten, would it be accurate to say that you don't know how much time you were away from your dad ... when you were working in the hog barn?

And according to prosecutors, that gave Todd the time to kill Amy. But Trysten says he was pressured to testify the way he did — pressured by Amy's stepfather.

Erin Moriarty: How would you describe the last eight years?

Trysten Mullis says his testimony at his father's murder trial didn't tell the whole story and if he could do it all over again, here's what he would want the jury to know about how long it took to get a drink of water that day.

Trysten Mullis: … I said I don't know how much time. I wasn't saying it could have been 20 minutes or whatever … It was a matter of seconds.

All he had to do, he says, was walk around a corner at the front of the barn.

Trysten Mullis: Right here is the hose that I drank out of that day.

Erin Moriarty: And so where do you drink out of it, like right here?

Trysten Mullis (drinks from the hose): Right out of the nozzle right here.

Erin Moriarty: You didn't do anything else in here?

Trysten Mullis: Nope. And then you walk right back in.

And that, he says, is just not enough time for his father to leave, kill his mother and come back. There were two ways Todd could have gone. Either through a door at the front of the barn —

Trysten Mullis: I would have seen him and I would have heard him.

Erin Moriarty: So what's the only other way he could have gone out?

Trysten Mullis: The only other way he could have gone out is to the end of the barn, all the way down at the end there.

Erin Moriarty: Then to get to the shed, how would he have to do that?

Trysten Mullis: would have to run all the way across the barn and then run all the way down.

Trysten Mullis: He'd have to jump the gate, run through the trees, go into the barn, do whatever, and run all the way back.

The round trip would have been about the length of four football fields.

Trysten Mullis: Come through the door, get back to the spot. Not be out of breath, not be panicked, not be, you know, frightened in any way, shape or form.

Erin Moriarty: … did your dad seem to be disheveled when — any time when you saw him there or out of breath or —

Trysten Mullis: I've had to grow up really fast … going from a 13-year-old kid now taking care of two … younger siblings … trying to lead them.

When his father was arrested for the murder of his mother, Trysten, his sister Taylor, then 11, and brother Wyatt, 9, went to live with Amy's family three hours away.

Peggy Munson (emotional): I'd always promised her that I would look after her children. … But little did I know they would be living with us.

Peggy Munson: It was hard for us too, because we were still grieving.

It was painful all around. The kids had to adjust to a new town and a new school. But for Trysten, there was no adjusting to the fact that he was living with family that he says believed his father was a killer.

Trysten Mullis: And I — to this day I've tried to get them to change their mind … and they still don't believe that he's innocent. … it's caused a lot of tension in that side of the family because of what they believe and what I believe.

So at 17, with the help of a lawyer, Trysten took action. He signed an affidavit accusing Amy's stepfather Randy and an attorney hired by Amy's family of pressuring him on how to testify at trial if asked about how long his father was out of his sight:

They said that if I did not answer the question with "I don't know" to the question then I would get in trouble for my mom's death and be sent to a jail for kids called juvenile detention and that I would be taken out of school and away from my friends.

Erin Moriarty: As you know, Randy … He said in his affidavit that that you had pressured him …

Randy Munson: Yeah. No, just tell the truth. …

Peggy Munson: Very much so. Because that's the last thing that we did with those kids is tell them to say anything — they speak their own mind … The truth is what we want them to say. Yeah, that was hard, very hard.

Today, Trysten does not want to talk about his affidavit.

Trysten Mullis: it's kind of a sensitive area.

But when he rewinds back through the murder trial, all he can see are mistakes and missed opportunities to prove that his mother's death was accidental — starting with his father's defense counsel. In a letter to his lawyer written from jail before the trial, Todd asked, "is there any 'expert' that could verify possibility of it being accident." In another, Todd made a rudimentary sketch of how he thought it happened.

But when the trial began Todd's defense attorney Gerald Feuerhelm didn't even argue it was an accident. He told the jury that Amy was murdered.