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Natalie Morales
Why have I asked my H Vac guy I found on angie.com to change my grandpa's trachea tube?
Ann Marie Green
Because I was so amazed by how quickly he replaced our air ducts, I knew I could trust him to change.
Natalie Morales
Pop Pop's tube while I was on vacation. Make it quick, young man.
Commercial Narrator
Aw.
Natalie Morales
See? Pop Pop trusts you.
Commercial Narrator
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Natalie Morales
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Ann Marie Green
50% off regular price for new customers. Upfront payment required. $45 for three months, $90 for six month or $180 for 12 month plan taxes and fees. Extra speeds may slow after 50 gigabytes per month when network terms. Welcome to Postmortem. I'm your host, Ann Marie Green. And today we're discussing the murder of Mary kay Hesse, a 17 year old high school student from Wahoo, Nebraska. She was killed in 1969. 55 years and multiple investigations later, one of the very first suspects, Joseph Ambrose, was finally arrested and charged with Mary Kay's murder. Joining me now is 48 Hours correspondent Natalie Morales. Natalie, you worked on this episode. It was. I mean, it was a doozy.
Natalie Morales
Yes, it was. And good to see you again, Ann Marie. In fact, this is one of the longest cold cases that 48 hours has been working on.
Ann Marie Green
Before we dive deeper. Just a reminder to everyone, if you haven't listened to this episode of 48 Hours, you're gonna find it in the podcast feed just below this one. Listen and then come on back for this conversation. Okay? So, Natalie, you know, watching the years tick by, I really didn't think that there was gonna be a resolution to this murder at all. And I wonder what it was that kept detectives coming back to the case over and over again when with each year, it like it would have been more and more of a long shot to get a resolution.
Natalie Morales
Yeah, you know, this was a real shock to the town of Wahoo. I mean, it really lost its innocence after the murder of Mary Kay hesse back in 1969. Murders there in this town were very Rare. But afterwards, people were afraid to go to Oahu because that's where the girl was murdered. It kind of developed that negative reputation and connotation. You, you know, and if you think back, I mean, this was, these were the days, 1969, it was the Sadie Hawkins dance girls would bring. And Mary Kay Hesse, in fact, was bringing her little straw pocketbook to school. I remember, in fact, having a bag very much like that. And even the lucky rabbit keychain was something that I even had as a kid growing up.
Ann Marie Green
It was like a time capsule reminding us of kind of a much more innocent time.
Natalie Morales
And when you go back to Wahoo, you know, it really does look a. We compared, you know, the footage throughout the hour from 1969 to then. We were a little bit of a time lapse to 1999. And here, here we are, 2026, covering this case again. And really not much has changed. A lot of the things there still remain the same. And another interesting people may think, well, Wahoo. Why does that sound so familiar? Well, David Letterman used to have a shtick on his show where he would check in with our home office in Wahoo. And we drove past the, what was the old phone booth, the old glass phone booth that you would see back in the day. And people would put post it notes on that phone booth. And that was the so called office in Wahoo that David Letterman was referring to.
Ann Marie Green
And just to bring people back to the case, this is how things unfold. That day, March 25, 1969, Mary Kay's parents reported her missing. That evening when she failed to come home from school, a witness reported seeing Mary Kay getting into a car with two men. Her body is then found in a ditch along a rural road. She has been beaten and she has been stabbed to death. Yeah, we know that when it comes to homicides, you know, those first few hours, those first few days, they are crucial when it comes to solving a case like this. Why was it so difficult to sort of nail down suspects for this murder in those early days, especially when there was an eyewitness who saw her getting into a vehicle?
Natalie Morales
Yes, and the police at the time did question all those witnesses. Investigators, you know, went about doing the job as best they could back then with the tools that they had. Investigators now, looking back on the case and the prosecutors, you know, they reminded us, 1969, I mean, this type of murder case, a homicide in Wahoo, Nebraska, that was unheard of. In fact, the Nebraska State Patrol had just started to broaden the scope of things that they Got involved with, like, criminal investigations also. It was. It was spread out over various different law enforcement departments. You know, the police department covered some of it. The sheriff's office had part of the case. The state patrol got involved. And some of the evidence of this case was even sent to the FBI, which was, that time, under J. Edgar Hoover. All was sent to J. Edgar Hoover's attention. And the current prosecutors say that the evidence was scattered all over the place across these different agencies. So that made sort of pinning down things a little more difficult.
Ann Marie Green
So then what sort of evidence did they have, you know, at that time?
Natalie Morales
Well, really, it came down to analyzing and. And taking stock of that crime scene. You know, they saw footprints in. Along the road that showed that it appeared that Mary Kay Hessey got out of the vehicle and it seemed like she was running. And they could tell this, according the investigators, back then, because the strides were long strides. And they also saw another shoe print by her footprints. Her school books were found along the side of the road, as well as that pocketbook that I mentioned stacked neatly on the road. So investigators believe that the killer might have placed them on the side of the road, realizing, I've got to get rid of this evidence. But this was long before the days of DNA testing, so all of that would be preserved somewhat, but yet it would take years for them to go back and analyze and look at the case again. Using new tools. With science advancing and catching up to.
Ann Marie Green
Where we are today, I thought it was really interesting that they relied a lot on the polygraph tests. Now, we know polygraph tests are, you know, I don't know how often they're used because we know that people can beat them. But Joseph Ambrose, they speak to him at the time. He's 22 years old. He's questioned because he was seen talking to Mary Kay weeks before the murder. He tells investigators that he was actually hanging out with a friend, Wayne Greaser. They were at a number of different locations the night of the murder. Both of the men, though, take and they pass polygraph tests. Nowadays, polygraphs are usually not admissible in court.
Natalie Morales
Yeah. And, you know, today, I mean, I think scientific research suggests that polygraph tests, they're generally not reliable. As you said, people can. Can beat those tests. Also, if you're nervous and you're taking a polygraph test, I don't know if you've ever been hooked up to one of those, but, you know, you get nervous when you're taking that. I. I had it done once, you know, just as a tool and Your levels are spiking just because you're nervous. And it could change the, the polygraph result. So Ambrose did pass that original polygraph, but we again, don't really know what exactly he was asked. And they didn't even look at, you know, Ambrose's car at the time. And it's believed, you know, if all of this happened, it happened within the car and outside of the car that would have been the crime scene. And also they never really compared the shoe print that they found frozen to Ambrose's, although Ambrose was a size 9 and a half, which turns out was the size of that print. But it would only be years later now, as recent investigators started putting the pieces together, that they would make that connection.
Ann Marie Green
And then in 1999, we have Sergeant Bob Frank, he picks up the case again. And 48 hours cameras were actually there following the investigation.
Natalie Morales
That's right. You know, we filmed Sergeant Frank. This was back when they formed this, this newly formed cold case team to tackle this case. And they worked on it for a year because this was a 30 year cold case at the time. So we at 48 Hours back then in 1999, were interested to see if the cold case team, using DNA technology, if they could find any new DNA evidence with the new tools and the science. So we filmed the team for quite a while and it was evident though at the time that the case didn't seem to be moving forward anywhere it remained cold. So the story was really put on the shelf. That footage also put on the shelf for us at 48 hours. But like we say, we always like to follow cases for as long as we can until there's some sort of resolution. And we became aware that an arrest had been made in 2024. And we found all the footage that we had and realized, boy, you know, we do have a lot here. And this would make for a fascinating update.
Ann Marie Green
And in watching the archival footage, I was sort of struck by how much access 48 hours had. I don't think we'd have the same level of access today.
Natalie Morales
I mean, it really was like being a fly on the wall in the investigation as it was carrying on. We, we went into the interrogation room with them. They made it seem like there was this so called cold case task force. They waxed up the tables, even waxed the chairs so that anybody that they brought in for questioning would be uncomfortable and like, it would be slick and sliding around. You see a bunch of names up on the whiteboard in the interview room. That was again, one of the tactics they Used just to try to make it seem like, oh, they're making a break in the case. Look at these names. Although a lot of the names were fake names. One of the investigators even put his own name on the whiteboard. So that kind of insight into a case. I don't think we've. We've seen something like that today. It shows, though, the lengths that the detectives went through to try to get some sort of break in the case and new information. Yeah.
Ann Marie Green
And you get some real insight into sort of how they're thinking about this investigation. Sergeant Frank scours these old case reports, and what he notices is that Joseph Ambrose and Wayne Greaser, they keep coming up over and over again in witness statements. So then he interviews people who knew the men at the time of the murder. And then eventually, he actually travels to Florida to speak with Joseph Ambrose himself. And we have some of that sound.
Commercial Narrator
We have a wonderful thing called DNA. Right. And we're gonna be able to show who she struggled with.
Natalie Morales
Okay.
Commercial Narrator
Again, you know, we have all these little bits of information here or there that fit together that you were there, not necessarily that you did it, but that you were there when it happened. That's yet to be proven. I mean, I wasn't there. Like I said, I had nothing to do with it. And you're free to take blood, anything you want.
Natalie Morales
You know, we even had incredible access. The crew that was there following Sergeant Frank at the time, they were parked right outside when. When they picked up Ambrose up for questioning. Ambrose has always been insistent, since shortly after the murder that he had nothing to do with this. He, though, as you heard, seemed to be cooperative. He even offered up his blood. But he knew investigators also had a search warrant for his house. So one of the few times we do see Ambrose get just a little bit agitated is when Frank brings up, you know, the man who told authorities that Greaser confessed that he and Ambrose had driven Mary Kay to that field area and that it was Ambrose who killed her. However, detectives at the time couldn't talk to Wayne Greaser anymore because he had died by suicide in 19. Given all of that, there was no match when it came to the DNA to Mary Kay's books or her clothes. So ultimately, it came down to this case, once again, stalling because, you know, the county attorney at the time felt there just wasn't enough to move forward in the case. They also. They were working off of a grant. They started to run out of money. So in 2000, Sergeant Bob Frank, unfortunately had to stop working on the case.
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Natalie Morales
Yeah, you know, it was up to the prosecutor. And like I said, this is a case that really hung over the community. So it was something that always remained on people's minds. Time though, as you know, was not on their side. Witnesses, of course, were dying, memories are fading and Ambrose was getting old. So prosecutors told us they felt it was now or never. And you know, Greene was the one who looked back at all the files. Once again he had to go scrounge various bureaus to find all these other pieces of evidence that were were widespread over various departments and agencies. And he tried to consolidate it, put it all together. He ended up re interview witnesses again. And what started off with just a couple of files ended up being boxes and boxes of files, and they really.
Ann Marie Green
Went all out running down leads. In 2019, a tipster reported that they had heard stories about men taking apart a car. Greene feels that the car looks an awful lot like one that Joseph Ambrose had actually driven at the time, and that the car was pushed into water. Shortly after Mary Kay's murder, this led investigators to search a local reservoir. It took five years to partially to search and then partially dredge this reservoir, and really they got scraps. So as I was watching this, though, I. I just, like. I wondered why that was so important to them, Especially considering that it didn't seem like they got much in the way of evidence.
Natalie Morales
Yeah, you know, Ted green was adamant that finding the car would be the ultimate piece of the puzzle that he really needed. It was what he viewed as the crime scene. He thought also that the murder weapon, the knife, could possibly still be in the car. Unfortunately, in this case, they came up with just little scraps of material which they felt could have been the material from the seats, from the inside of the car, because it kind of looked like that. You know, the color of the material they would expect. But they didn't get to the bottom of the reservoir because they couldn't end up dredging the whole reservoir.
Ann Marie Green
Mary Kay's body was exhumed for a second autopsy. Now, you know, after the body was buried for 50 years, I assumed that there really wouldn't be much in the way of evidence Because I assumed there'd be more decompos. But I want to play a portion of the interview that you had with Richard register, the deputy county attorney, and Jennifer jochim, the Saunders county attorney, where you talk about just how well preserved Mary Kay's body was when they revealed.
Commercial Narrator
Her after they took off the drapings.
Natalie Morales
Or whatever that thing she had on her, her legs looked like she was in just the day before.
Ann Marie Green
It was remarkable.
Natalie Morales
Remarkable.
Commercial Narrator
The thing that was just frightening is all. Is her goosebumps formed on her legs during the autopsy.
Natalie Morales
Hmm. That's what Ted was saying. I did not know that could happen. Almost as if her body was trying to tell you something from the grave. Yeah, just completely remarkable. I had never heard of that being a possibility that the body would have goosebumps like that. But apparently, according to the prosecutors, they said, the medical examination examiner said that sometimes when a body is re exposed to oxygen that it can have sort of that. That reaction like that. What was fascinating about the second autopsy and what that revealed, that allowed them to get a much Bigger clue into who could have done it was they they noticed there were more stab wounds in the autopsy than was initially reported. And also, according to investigators, the manner in which Mary Kay was stabbed was consistent with how slaughterhouse workers are taught to kill animals. And I bring that up because Joseph Ambrose worked on the kill floor of a slaughterhouse, so he knew how to kill animals. He had the weapons and the knives to kill animals. And the way Mary Kay Hesse was killed, according to the prosecutors and the medical examiner, upon the second autopsy, they felt that it looked like somebody who knew what they were doing.
Ann Marie Green
So then, in 2021, Greene travels to Ohio now to interview Ambrose again. This guy kind of gets around because every time they try to track him down, he's living in a different state. Do we have any idea just what was going on in his life over the decades between, you know, Mary kay's murder and 2021?
Natalie Morales
Yeah, I mean, it's hard to really pin it down. We do know that according to authorities, Ambrose had had six wives. He also reportedly was a truck driver, perhaps for some of that time, according to the prosecutors. But when Ted Green goes to interview him this time, he asked him about claims that people had reported at the time that they had witnessed blood on his car around the time of the murder. And Ambrose admitted there was blood on his car because he said he probably ran over a deer or a rabbit. But the blood was reported on the back rear fender. And that is not typically where you run over an animal. You don't really back up into the animal. You would hit them moving forward. So the fact that Ambrose said, yes, that there was blood on his car, Ted Green felt that was a revealing part of the interview.
Ann Marie Green
Right. I just thought to myself, either a deer or a rabbit, I mean, yeah.
Natalie Morales
You would think you'd be able to narrow it down and you would remember what you hit.
Ann Marie Green
Yeah, if you hit a deer, you probably never forgot that, you know, but.
Natalie Morales
There'S a lot more damage to the car as well.
Ann Marie Green
Absolutely. So by 2023, Green feels like he has compiled enough evidence. He shows his findings to the county attorney, and then that's presented in front of a grand jury. And the grand jury indicts Ambrose for first degree murder for the murder of Mary Kay Hesse. Do we know what the collection of evidence was that convinced the grand jury?
Natalie Morales
So it was, again, Ted Greene putting all of the pieces together to give a fuller picture to this puzzle. He had presented new witness statements, Ambrose's interviews, because he went back to the old interviews, and it compared to what Ambrose was telling him. Now with the new interview and then of course, the evidence of the shoe print. Well, Ted Green says the shoe prints at the murder scene appear to match Ambrose's size, the size nine and a half. And also the pattern was a prison issued shoe, that Ambrose, who had served time, he was on parole at the time, had been new to the town, but he had been given prison issued shoes. So it could have matched the pattern that was found at the crime scene.
Ann Marie Green
So they are preparing to go to trial. And then in July of 2025, before the case can be heard in a courtroom, prosecutors reach a plea deal. So Ambrose agrees to plead no contest to the charge of conspiracy to commit first degree murder. But because the crime was governed by the sentencing guidelines in 1969, the charge carries a very light penalty. Just two years behind bars, Ambrose is sentenced to the maximum. It's two years.
Natalie Morales
Right. And with the good time sentencing reduction law, Joseph Ambrose sentence was actually cut in half. So with time served, he was actually released in November of 2025. Which for the murder that has haunted this town for so long, 55 years for him to serve just a little over a year. You know, for the family, it was a real shock and almost a slap in the face. They were not happy about that whatsoever. They wanted to bring the case forward to a jury, they wanted the case to go forward in trial. But Ambrose, he said he did take this plea deal because he, because of his age, he was on oxygen, he had some health issues, he was in his late 70s. He may not have lived until trial. To this day, though, he maintains his.
Ann Marie Green
Innocence with this plea deal, he didn't really have to talk about the case at all. He didn't have to address any of the accusations. He didn't have to reveal any details about the murder. So you can't get, you can understand why viewers, and I count myself among them, would feel like a little unsatisfied with this result.
Natalie Morales
What the prosecutors told us is while they understand and they see the family's perspective, of course they would have loved to have been able to have charged him and to really have seen him, you know, go to trial. They do believe Ambrose did this, as does the family. But the prosecutors really felt that their case faced several challenges. This is 55 years later. The possibility of witnesses not being around much longer might have even died. Prior statements could be viewed as hearsay and that would be inadmissible in court. You know, the murder weapon also was never found. There was no DNA evidence and they weren't confident that they were gonna be able to get a conviction from a jury. Ambrose also had an experienced attorney who was provided by the state. That attorney was able to get Ambrose the best plea deal possible.
Ann Marie Green
It's very difficult. Not only is it difficult to investigate decades old cases, but it's difficult to put together a 48 Hours episode. So you guys did an excellent job. I really sort of felt like I was transported kind of back in time and then forward again. And even though I never went to trial, you know, we did get some answers.
Natalie Morales
Right. In the end, there is, as you said, finally an answer and some form of justice for Mary Kay Hessey's murder.
Ann Marie Green
Absolutely. Really interesting hour. Natalie, thank you so much.
Natalie Morales
Thank you.
Ann Marie Green
And if you like this episode, please rate and review on Apple Podcast or Spotify. I'm like a lion.
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Natalie Morales
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Podcast Summary: 48 Hours – Post Mortem | The Girl From Wahoo (February 17, 2026)
This episode of “Post Mortem,” hosted by Anne-Marie Green, offers a behind-the-scenes exploration of CBS News' reporting on the decades-long investigation into the 1969 murder of Mary Kay Hesse, a 17-year-old high school student from Wahoo, Nebraska. Award-winning correspondent Natalie Morales joins to recount the intricate, frustrating, and ultimately partially resolved search for justice in one of the longest-running cases covered by 48 Hours.
“It really was like being a fly on the wall in the investigation as it was carrying on.”
—Natalie Morales [10:14]
“If you hit a deer, you probably never forgot that…”
—Anne-Marie Green [21:43]
“There’s a lot more damage to the car as well.”
—Natalie Morales [21:48]
[23:06] Before trial, Ambrose pleads no contest to conspiracy to commit first-degree murder. Because 1969 sentencing laws apply, he receives just a two-year sentence, later halved with credit for time served. Ambrose is released after a little over one year in prison ([23:40]).
The prosecutors and family believe Ambrose was guilty, but the plea deal avoided the possibility of an acquittal in a trial complicated by hearsay, fading witness memories, and missing forensic evidence ([24:52]).
“[Ambrose] didn’t really have to talk about the case at all. He didn’t have to address any of the accusations...”
—Anne-Marie Green [24:28]
On the impact of the crime:
“I mean, it really lost its innocence after the murder of Mary Kay Hesse back in 1969.”
—Natalie Morales [02:28]
On the cold case task force tactics:
“They waxed the chairs so that anybody that they brought in for questioning would be uncomfortable and... sliding around.”
—Natalie Morales [10:14]
On the exhumation:
“Her legs looked like she was in just the day before. It was remarkable… The thing that was just frightening is... her goosebumps formed on her legs during the autopsy.”
—Anne-Marie Green, Natalie Morales, Commercial Narrator [18:31-18:47]
On the plea deal’s shortcomings:
“For the murder that has haunted this town for so long, 55 years, for him to serve just a little over a year. You know, for the family, it was a real shock and almost a slap in the face.”
—Natalie Morales [23:40]
On unresolved justice:
“...with this plea deal, he didn't really have to talk about the case at all.”
—Anne-Marie Green [24:28]
The tone throughout is empathetic, methodical, and at times somber—reflective of the profound loss and generational impact on a small community. Morales and Green candidly acknowledge the bittersweet nature of the case’s resolution.
“In the end, there is... finally an answer and some form of justice for Mary Kay Hesse's murder.”
—Natalie Morales [26:08]
For listeners seeking a comprehensive, yet humane look at the persistence and frustration inherent in solving a cold case, this episode provides both gripping narrative and honest reflection on the limits of justice and closure.