A Nebraska girl went looking for a date to a high school dance. One week later, she was murdered.

On March 25, 1969, 17-year-old Mary Kay Heese never returned home from school in Wahoo, Nebraska. Hours later, her body was found beaten and stabbed to death on the side of the road outside of town. 

Investigators tried to retrace Mary Kay’s last known whereabouts. One witness saw Mary Kay get into a car with two men on a street corner near her home. But investigators at the time were unable to figure out who was in that car. Weeks turned into months with no arrests. Mary Kay’s murder would remain unsolved for decades.

“48 Hours” correspondent Natalie Morales reports on how the murder was finally brought back into focus in “The Girl from Wahoo,” an all-new “48 Hours” airing Saturday, Feb. 14 at 10/9c on CBS and streaming on Paramount+.

In 2015, a new investigation was launched. Ted Green, a criminal investigator with the Saunders County Attorney’s Office, was assigned to the case.

“Every criminal investigation is a puzzle,” Green told “48 Hours.” For Green, part of figuring out that puzzle was learning more about Mary Kay Heese.

Mary Kay’s younger cousins, Mark Miller and Kathy Tull, remember Mary Kay as a happy person who always looked out for them. But they said that happiness was sometimes challenged by the struggles of adolescence.

Green learned Mary Kay came from a strict home under the eyes of watchful parents. It was a different situation at high school. “There was a group of girls that would get her together and put makeup on her at the beginning of the day and change her clothes out,” Green said.

“She wanted to fit in,” Miller told “48 Hours.”

Part of that desire to fit in was Mary Kay’s wish to attend the local Sadie Hawkins dance — a popular event at that time where the girls ask the boys to attend.

Tull told “48 Hours” that the shy Mary Kay struggled to find a date. Tull still has a letter from Mary Kay, written a week before her murder, asking her cousin Jerry to attend the dance with her.

“If we come over to get you on Friday the 28th or Saturday the 29th, will you go to the Sadie Hawkins dance with me?” Mary Kay wrote in the letter. “You can wear sportswear (not a tuxedo or anything) because it’s not a formal dance […] Don’t bring any money to get in because the girls are to pay for it all including the tickets and food.”

As Green learned more about Mary Kay, he came to one conclusion. “She wouldn’t get into a car with somebody that she didn’t know,” he said.

The pieces of the puzzle were coming together for Green, who focused on two names that kept coming up in the old case files: Joseph Ambroz and Wayne Greaser, both interviewed in the days following Mary Kay’s murder.

Joseph Ambroz, 22, was living in Wahoo and worked at a slaughterhouse at that time. He was also on parole after serving time for forgery and escaping custody.

Greaser was friends with Ambroz. “He was just that wannabe kid who wa just following around Ambroz,” said Deputy Saunders County Attorney Richard Register, who worked on the case. 

Green and Register told “48 Hours” Ambroz knew Mary Kay. They both frequented the same café and had mutual friends. Green and Register also believe Mary Kay thought Ambroz was not a threat, but an opportunity to fit in with the crowd.

Green believes Ambroz and Greaser took Mary Kay to a well-known party spot near town and at some point Mary Kay tried to flee the car. Green says he believes Ambroz went after her and eventually stabbed her to death.

“She just wanted to get a boy to go to the dance with her. And unfortunately, the dance she went to was her death,” Register said.

More than five decades after Mary Kay Heese was found dead, 77-year-old Joseph Ambroz was arrested for her murder.

In July 2025, Ambroz took a plea deal and pleaded no contest to conspiracy to commit first- degree murder. He was sentenced to two years in prison.  Greaser, who had died by suicide in 1977, was named as the other person conspiring to kill Mary Kay.

For Mary Kay’s cousins, the plea deal and sentence were an injustice. They say Ambroz stole Mary Kay’s future.

“He got all these years to live, and Mary Kay never had the chance to live,” Miller told “48 Hours.”