Defense alleges prosecutorial misconduct in indictment of man for 1969 Wahoo murder

The man accused of murder in one of Nebraska’s oldest cold cases is seeking to have his indictment thrown out for prosecutorial misconduct.

Joseph Ambroz, 78, was indicted last year by a grand jury in Saunders County for the 1969 murder of 17-year-old Mary Kay Heese in Wahoo. The girl was found stabbed to death in a ditch a few miles outside of town the morning after her parents reported her missing when she failed to return home from school.

At a brief hearing on Monday, Saunders County District Court Judge Christina Marroquin set another hearing for July 31 to allow for time to review the extensive grand jury record and exhibits.

In a motion to quash, or dismiss, the grand jury indictment, Ambroz’s attorney, Matthew McDonald, said prosecutors failed to show the grand jury multiple pieces of evidence that could have weighed in favor of Ambroz. If Marroquin declines to dismiss the case, McDonald is asking the judge to remove the Saunders County Attorney’s Office and the Nebraska Attorney General’s Office from the case – including prohibiting testimony from Ted Green, the main investigator of the case for the Saunders County Attorney’s Office.

A special prosecutor outside of the Saunders County Attorney’s Office has already been appointed. Bruce Prenda, the county attorney of Colfax County, was appointed as special prosecutor in March, though the Saunders County Attorney’s Office remains involved in the prosecution.

Marroquin will also consider a plea in abatement from Ambroz, which claims that there was insufficient evidence presented to the grand jury to justify the indictment. There was no oral argument on that motion on Monday, and Marroquin said she would issue a written order at a later date.

Then a junior at Wahoo High School, Heese was last seen at about 5 p.m. on March 25, 1969, as she walked home from track practice after grabbing a hot chocolate from a local cafe. When she didn’t return home that evening, Heese’s parents called the police.

In the early morning hours of March 26, 1969, a farmer notified police after finding school books scattered along a country road about four miles outside of Wahoo. When police arrived to search the area, they found Heese’s body in a ditch nearby. Her cause of death was multiple stab wounds to the stomach, according to newspaper reports at the time, and there was no sign of sexual assault.

As decades went on without an arrest, news reports began to provide new and conflicting information about the discovery of Heese’s body. While initial articles from The Omaha World-Herald said the books were scattered along the road as if they had been thrown out of a car window, a 1999 article from the Associated Press said the farmer found a “neatly stacked pile of books” along the road.

That AP article also said Heese was wearing white gloves that were soaked in blood – a detail not noted in early newspaper reports – and suggested that she had “bolted from a car and run down the road, chased by an attacker.”

Investigation stalled early

Investigators hit a roadblock early on in the investigation.

“We have questioned, either here or in other cities, a total of 685 persons,” then-County Attorney Robert Sullivan told The Omaha World-Herald in 1970. “But we are no closer to a solution today than we were when we found the body alongside that road.”

The case remained cold for more than 50 years before Ambroz was indicted – but, according to court documents, Ambroz was interviewed by police in connection with the murder at least four times between 1969 and 2021.

On the night of Heese’s murder, according to Ambroz’s first statement to police on April 1, 1969, he and a friend drove to Fremont to look for a girl. They located the girl’s house, but when she wasn’t at home, they drove to Mead, Nebraska, and picked up Ambroz’s girlfriend. They stayed with his girlfriend from about 8:45 p.m. until 9:30 p.m., according to both Ambroz and his friend.

Though few details exist in court records of Ambroz’s later interviews with police – which took place on April 17, 1969; Sept. 26, 1999; and in 2021 – prosecutors claim he changed his story. Investigators determined that Ambroz did not have a “valid alibi.”

Ambroz took at least three polygraph examinations throughout the course of the investigation. According to court documents, he passed the first two examinations in 1969 with no sign of deception, while the third, completed in 1999, showed signs of deception.

Polygraph tests, sometimes called lie detector tests, were integral to the early investigation: Investigators polygraph tested every single male student at nearby schools, according to court documents. The tests have since been found to be unreliable and are not typically permissible as evidence at trial, though prosecutors may present polygraph evidence to a grand jury to make a charging decision.

The case was administratively closed in 2009 before it was reopened in recent years. Heese’s body was exhumed last year prior to the indictment.

Key witnesses lead to grand jury indictment

A grand jury was convened in Saunders County in October and November of 2024. In November, the jury handed down a one-count indictment against Ambroz, charging him with first-degree murder.

Grand jury proceedings are required in Nebraska when a person dies in law enforcement custody, but are otherwise uncommon in typical charging decisions. The work of a grand jury is secretive, and it requires a jury of 16 people and three alternates to decide if probable cause exists to determine the accused committed a crime. The accused does not have the opportunity to present evidence or rebuttal to the state’s claims during grand jury proceedings.

Grand jury transcripts in this case are not likely to be made public, but court documents provide some information about what was presented.

A brief from Ambroz’s defense team suggests that the grand jury heard from a “key witness” who claimed to know that Ambroz killed Heese, because a third party told the witness that he was with Ambroz during the murder. That third party has been dead since the 1970s, according to court records.

Ambroz’s ex-wife was granted immunity to testify at the grand jury, prosecutors said on Monday. She initially told police in the days after the murder that she had been with Ambroz at the time of Heese’s killing.

DNA was also a crucial issue during the grand jury proceedings, and in Ambroz’s motion to dismiss the indictment.

According to briefs from both the defense and prosecution, DNA was obtained from Heese’s pants, sweater and scarf. The DNA has been tested multiple times, and though two unique DNA profiles were present, Ambroz was not identified as a contributor. Hairs belonging to an unidentified female were also found on Heese’s coat.