Ted Green

And 48 Hours cameras followed Sergeant Bob Frank as he worked the case.

And we spoke with Frank again in 2025, now retired from the state patrol.

To try to get to the truth, Frank, in 1999, scoured the old case reports.

He noticed that Joseph Ambrose and Wayne Greaser, the men who were each other's alibis, kept coming up in witness statements.

Greaser had died by suicide in 1977.

Ambrose was long out of jail, having served a year and a half for that parole violation after Mary Kay's murder.

He had moved around and worked as a truck driver.

Bob Frank knew at some point he would want to talk to Ambrose, but first wanted to take a new look at the old evidence.

In 99 now, are you hoping you're going to get some sort of DNA?

So here's the evidence bag.

By 1999, when Sergeant Bob Frank led the Nebraska State Patrol's cold case unit, advances had been made in forensic science that were not available in 1969 when Mary Kay Hesse was murdered.

48 hours cameras filmed Frank going through Mary Kay's belongings as he looked for DNA and fingerprints.

Among the items tested were Mary Kay's school books, found stacked at the scene.

The theory was that Mary Kay left the books and her purse in the car.

The killer noticed the items and, not wanting to be linked to her belongings, dumped them.

A fingerprint examiner worked to find and lift prints off the school books, including one titled, Building a Successful Marriage.

Were there any fingerprints that came forward?

They also tested Mary Kay's clothing.

Frank spoke several times with Mary Kay's mother, Dorothy, over the course of his investigation.

48 Hours spoke with her as well in 1999.