On March 25, 1969, 17‑year‑old Mary Kay Heese, a high‑school junior from Wahoo, Nebraska, did not come home after school. Her disappearance set off a townwide search. Near midnight a farmer found Mary Kay’s purse and schoolbooks stacked beside a rural road; not far away her body lay in a ditch. Investigators later concluded she had been beaten and stabbed 14 times. Her shoes, tire tracks and a castable shoeprint were documented at the scene; no knife was recovered.
The killing shattered Wahoo’s sense of safety. Mary Kay’s family remembered her as shy and eager to fit in — she practiced twirling and hoped to find a date for a school dance. Early witness accounts placed her getting into a two‑person car at a street corner shortly after school. Police questioned many local men and used polygraphs, but investigative follow‑up in 1969 was uneven: cars were not always checked for blood, shoe evidence was not consistently compared to casts, and DNA testing did not exist.
Two names recur in the original files: Joseph Ambroz and Wayne Greaser. Ambroz, 22 at the time, was new to town, on parole for prior offenses and employed on a slaughterhouse kill floor. Some people remembered him talking with Mary Kay and making remarks that suggested sexual interest. Greaser and Ambroz were reported to be each other’s alibis.
The case stalled and then largely cooled. For decades it remained unsolved. In 1999 the Nebraska State Patrol created a Cold Case Unit, and Sergeant Bob Frank re‑examined the old reports and evidence as forensic science advanced. He reinterviewed witnesses, retested clothing and books for prints and DNA, and traveled to Florida to question Ambroz. Ambroz denied involvement; DNA from his samples did not match material tested on Mary Kay’s possessions, and polygraph results were inconclusive. Much of the 1969 documentation consisted of second‑hand statements. Frank compiled what he could and took it to prosecutors, but then there was still not enough to charge anyone.
The investigation lay largely dormant until 2015, when Saunders County investigator Ted Green began assembling decades of scattered reports, memos and witness statements. Green re‑interviewed people who had been in town in 1969 and pursued leads that had been previously overlooked or dismissed: recollections that Ambroz had talked about Mary Kay, comments suggesting he wanted her, accounts suggesting an argument between Ambroz and Greaser on the night she vanished, and a co‑worker’s recollection that Ambroz said something to the effect of preferring a short jail term over life — a statement investigators saw as possibly indicating motive tied to parole risk.
A pivotal public tip arrived in 2019 through a Facebook page set up by a friend of the family. The tipster recalled long‑running local rumors that a car like Ambroz’s — described as a two‑tone 1956 Chevy — had been dismantled and pushed into a nearby reservoir shortly after the murder. Green followed the lead and, working with civilian dive team Adventures with Purpose, recovered metal fragments and fibers from the reservoir that were consistent with a car interior. The team’s finds could not conclusively identify a specific vehicle without draining the reservoir, which was not practical.
Back on land, Green pursued additional forensic avenues. In 2024 authorities obtained permission to exhume Mary Kay’s remains for a second autopsy. Remarkably well preserved after 55 years, the body was re‑examined by a pathologist. Investigators say the wound patterns were consistent with techniques taught to slaughterhouse workers — ways to sever or stab used in animal processing — which matched the kinds of knives and methods Ambroz would have known from his kill‑floor job. That autopsy finding was combined with other circumstantial evidence: a shoeprint at the scene corresponded to a size Ambroz wore and had tread similar to prison‑issue footwear he might have been wearing; witness statements placed Ambroz and Greaser in the area that night; and several witnesses reported things the men had allegedly said about the incident.
In 2021 Green interviewed Ambroz, who was then living elsewhere and appeared frail. Ambroz told Green his car had blood on the left rear fender the night of the homicide and said the blood came from hitting an animal. Green concluded that the blood could have been Mary Kay’s and that she may have been pinned on the trunk. Green assembled the witness statements, shoe and autopsy evidence, the reservoir tip and other investigative work and presented it to the Saunders County attorney.
A grand jury later indicted Joseph Ambroz on a charge of first‑degree murder. Prosecutors acknowledged the case would be difficult at trial: no murder weapon was available and there was no DNA directly linking Ambroz to Mary Kay. Still, they believed the cumulative evidence and witness accounts were sufficient to proceed. Ambroz, then in his late 70s, was arrested on November 18, 2024, in Oklahoma and extradited to Nebraska.
Months later prosecutors and defense attorneys negotiated a plea. In July 2025 Ambroz pleaded no contest to conspiracy to commit first‑degree murder; the plea named the now‑deceased Wayne Greaser as a co‑conspirator. A no‑contest plea does not amount to an admission of the underlying facts, and Ambroz did not provide details about Mary Kay’s death. The agreement provoked anger and heartbreak among Mary Kay’s relatives and some investigators. Saunders County officials said they accepted the deal because of evidentiary challenges, the loss of witnesses over more than five decades, and the difficulty of securing a conviction beyond a reasonable doubt at trial.
Because the killing occurred in 1969, sentencing rules from that time applied. The maximum penalty for conspiracy to commit murder in 1969 was two years; with Nebraska’s good‑time credits and credit for time already served, Ambroz’s sentence was reduced and he was released in November 2025. His attorney said Ambroz maintained his innocence and accepted the plea because of his age and health.
For Mary Kay’s family and the Wahoo community, the arrest and legal resolution did not erase decades of unanswered questions. Investigators note that the case illustrates both the possibilities and the limits of cold‑case work: new forensic methods, persistent re‑investigation and community tips can revive and advance very old cases, but lost witnesses, degraded or incomplete evidence and legal constraints tied to when a crime occurred can prevent a full accounting of what happened. The effort brought new attention and some measure of official action after more than half a century, but many in Wahoo continue to seek a clearer, more complete resolution.