March 25, 1969,

• After School Mary Kay attended Wahoo High School track team try-outs.
• 4:30 PM – On the way back from practice she stopped at the Wigwam Cafe in downtown Wahoo for a hot chocolate.
  
• 5:00 PM – Neighbors saw her walking near the intersection of 12th and Linden streets in Wahoo, just five blocks from her home.
• 7:00 PM – She never made it home, She was reported missing by her family
  

March 26, 1969

• 12:00 AM a farmer found her schoolbooks scattered along a county road approximately four miles southeast of town.
• 12:30 AM Nearby, alerted police after discovering schoolbooks scattered along a county road about four miles southeast of town.
• Officers located Mary Kay Heese’s body, fully clothed in a ditch, with her white gloves stained with blood.
  

Investigation and Autopsy

• Evidence at the scene suggested she had fled from a vehicle, running down the rural road while being pursued. Her attacker eventually caught up with her, leading to a struggle on the road that continued into the ditch, where her body was ultimately found. Authorities found no evidence of sexual assault.
• She was stabbed multiple times in the chest and stomach. Her body was found after midnight on March 26, 1969.
• The weapon used to kill her was never found.” and evidence indicated she had tried to escape her attacker before succumbing to her injuries.

March 29, 1969

• Mary Kay was laid to rest in Blair Cemetery, located in Blair, Washington County, Nebraska.

2006

• A grant for DNA testing of Nebraska cold cases breathed new life into the case

2007

• Dorothy Heese, died in 2007 without ever learning what happened to her daughter. Her father had also died already.

2009

• Local man in his early 20s was seen drinking heavily that day was as a suspect, but there was not enough evidence to make an arrest. That man eventually took his own life a few years after Heese’s killing, the investigator said.
• Investigators had declared the case “administratively closed.”

2014

• Saunders County Attorney Scott Tingelhoff said that the genetic material collected from the scene is now being subjected to additional testing, though he said the DNA was not what lead investigators to their current line of investigation.

The area near County Road J where she was found was the one that leads to a place commonly referred to in the community as “The Grove.” In Heese’s day, it was the site of a number of illicit activities. “And we’re considering that the location may have more significance than we previously thought,” said Tingelhoff.

Despite extensive investigations, her murder remains unsolved. Over the years, law enforcement has revisited the case, utilizing advancements such as DNA testing and conducting interviews with potential witnesses, but no definitive suspect has been identified.

September 2024

• Mary Kay’s body was exhumed from the family plot at the Blair cemetery

November 18, 2024

• Arrest: Joseph A. Ambroz, 77, was arrested for one count of first-degree murder. A warrant was issued for Ambroz’s arrest after a Sunders County Nebraska Grand Jury indicted him for 17-year-old Mary Key Heese’s death.
• He was taken to the Kay County Detention Center in Oklahoma, where he will be held until he is extradited to Nebraska. 

Joseph A. Ambroz was imprisoned in the 1960s for forgery and escape. He then moved to his mother’s home in Wahoo, where Heese’s family lived. Records show that he violated parole shortly after her murder in 1969 and then served more time. After his release, Ambroz moved around the country, holding more than two dozens addresses across nine states ahead of his arrest.