Post Mortem | The Girl From Wahoo

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2:57Natalie Morales:Welcome to Postmortem. I'm your host, Anne-Marie Green, and today we're discussing the murder of Mary Kay Hessey, 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.

3:32Anne-Marie Green:Yes, it was. And good to see you again, Anne-Marie. In fact, this is one of the longest cold cases that 48 Hours has been working on.

3:39Natalie Morales:Before we dive deeper, just a reminder to everyone, if you haven't listened to this episode of 48 Hours, you're going to find it in the podcast feed just below this one. Listen and then come on back for this conversation. OK, so, Natalie, you know, watching the years tick by, I really didn't think that there was going to 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 seemed like it would have been more and more of a long shot to get a resolution.

4:15Anne-Marie Green: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 Wahoo because that's where the girl was murdered. It kind of developed that negative reputation and connotation. And, 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 pocket book to school. I remember, in fact, having a bag very much like that.

4:53Anne-Marie Green:And even the the lucky rabbit key chain was something that I even had as a kid growing up.

5:00Natalie Morales:It was like a time capsule reminding us of kind of a much more innocent time.

5:05Anne-Marie Green:And when you go back to Wahoo, you know, it really does look a lot. 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 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.

5:48Anne-Marie Green: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.

5:58Natalie Morales:And just to bring people back to the case, this is how things unfold that day. March 25th, 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. 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?

6:44Anne-Marie Green: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 spread out over various different law enforcement departments. You know, the police department covered some of it.

7:20Anne-Marie Green: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 at 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.

7:47Natalie Morales:So then what sort of evidence did they have, you know, at that time?

7:52Anne-Marie Green:Well, really, it came down to analyzing and taking stock of that crime scene. You know, they saw footprints along the road that showed that it appeared that Mary Kay Hesse got out of the vehicle. And it seemed like she was running and they could tell this, according to 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, you know, I've got to get rid of this evidence.

8:35Anne-Marie Green: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 where we are today.

8:53Natalie Morales: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.

9:31Anne-Marie Green: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 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 had it done once, you know, just as a tool, and your levels are spiking just because you're nervous and it can change 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.

10:12Anne-Marie Green: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, Ambrose's, although Ambrose was a size nine 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.

10:39Natalie Morales: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.

10:47Anne-Marie Green:That's right. You know, we filmed, Sergeant Frank, this was back when they formed 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.

11:30Anne-Marie Green: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.

11:51Natalie Morales:And in watching the archival footage, I was sort of struck by how much access 48 Hours had. I don't think we would have the same level of access today.

12:00Anne-Marie Green:I mean, it really was like being a fly on the wall in the investigation as it was carrying on. 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.

12:37Anne-Marie Green: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 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.

12:56Natalie Morales:Yeah, 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. We have a wonderful thing called DNA, and we're going to be able to show who she struggled with. Again, we have all this little bits of information here or there that fit together that you were there.

13:40Natalie Morales: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. You're free to take blood, anything you want.

13:51Anne-Marie Green:You know, we even had incredible access, the crew that was there following Sergeant Frank at the time. They were parked right outside 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.

14:38Anne-Marie Green:However, detectives at the time couldn't talk to Wayne Greaser anymore because he had died by suicide in 1977. 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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16:09Natalie Morales:Welcome back. So the case is cold. And then fast forward to 2015. Enter Ted Green. He is an investigator for the Saunders County Attorney's Office. And he starts looking into the Mary Kay Hesse murder. This is a small town, I presume with limited resources, yet, you know, they still sort of managed to scrounge up the money to keep this investigation open. How were they able to do that?

16:39Anne-Marie Green: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, Green 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 widespread over various departments and agencies. And he tried to consolidate it, put it all together.

17:21Anne-Marie Green:He ended up reinterviewing witnesses again. And what started off with just a couple of files ended up being boxes and boxes of files.

17:32Natalie Morales:And they really went all out, running down leads. In 2019, a tipster reported that they had heard stories about men taking apart a car. Green 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 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.

18:20Anne-Marie Green: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.

19:00Anne-Marie Green:her.

19:02Natalie Morales: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 decomposition. But I want to play a portion of the interview that you had with Richard Register, the deputy county attorney, and Jennifer Joachim, the Saunders County attorney, where you talk about just how well-preserved Mary Kay's body was. When they revealed her after they took off the drapings or whatever that thing she had on her, her legs looked like she was in just the day before.

19:45Anne-Marie Green:It was remarkable.