Terre Haute police chief Shawn Keen knew he would be taking a risk by using up the last human sample he had from a 47-year-old crime scene, but he had a feeling the gamble would pay off.

This week, it did.

Using DNA testing, Keen solved the 1972 murder of Indiana college student Pamela Milam — a crime that happened two years before the police chief was born.

Following a trail of DNA breadcrumbs that started with a genealogy profile, Keen managed to put to rest a case he'd been struggling with for more than a decade.

“I had to find answers for the family,” he said. “Forty-seven years later, it still matters to them.”

Milam was last seen leaving a sorority event at Indiana State University in the fall of 1972. The 19-year-old woman's father and sister later found her bound and gagged in the trunk of her car. She had been sexually assaulted and left for dead.

Several pieces of evidence, including a sperm sample from Milam’s blouse, were recovered at the time.

Keen took on the case in 2008 when he was assistant chief of investigations. Using nearly half-century old evidence, he began pursuing every possible lead. He hit dead end after dead end before learning about genealogy-based DNA testing.

“After researching it, it seemed to be pretty amazing,” he said. “Through this, you would have much better luck finding a relative of a suspect than a suspect.”

The sperm sample, which remained in cold storage, was taken in and out for various testing, Keen said. By 2018, there was only a shred left.

Terre Haute Chief of Police, and lead detective on the cold case of Pamela Milam's 1972 homicide, Shawn Keen speaks during a news conference at Indiana State University in Terre Haute, Ind., on May 6, 2019. Police say Jeffrey Lynn Hand, just identified as the killer of Pamela Milam, an Indiana State University student in 1972, was killed in a shootout with police six years later. Austen Leake / The Tribune-Star via AP

“I really had to weigh my options at this point,” he said. “Either I use this now, or wait a few more years for even better testing to come around."

If the sample produced a non-definitive result, Keen would have squandered his last shot at science-based testing.

He believed that the test would crack the case, and submitted the sample to Parabon NanoLabs, a Virginia-based company that works with law enforcement using DNA, ancestry databases and traditional genealogical work.

The results led to a woman who had relatives in Washington, Indiana, a town 70 miles from Terra Haute, Keen said. Samples from that woman led to two more relatives who also gave DNA samples, he said.

Ultimately, the genealogy-based testing pointed police to Jeffrey Lynn Hand, a man with criminal background that included multiple crimes such as kidnapping and murder.

Hand died during a police shootout in 1978, so Keen reached out to his widow.

The call took her by surprise.

“It was awkward at first,” Keen said. “We were asking her questions about a husband that had been dead for 43 years."

But she fully cooperated as Keen questioned her for nearly three hours.

The woman's memory was impeccable, Keen said. She could recall details from decades ago, including the make and model of the car Hand used to drive. She also revealed that Hand was abusive and didn't allow her to ask him anything about his whereabouts, the chief said.

“It didn't come as a shock to her that Hand did what he did,” Keen said. "Considering how he died, she wasn't surprised by it."

The police chief then contacted Hand’s three children, who were very young when Hand died.

Even though they never knew their father, they felt bad about what he did, Keen said. They had remorse and wanted to do whatever they could to help the case.

Two submitted a DNA sample, which is what conclusively pinned down Hand as the perpetrator, he said.

Keen said making the call to Milam’s family was the best call he’s ever made. “The family called me every year to tell me they supported me,” he said. “They were my motivation, what kept me going.”

And though the Milam case is no longer cold, Keen said his work is not done.

He believes Hand was involved with other crimes in neighboring counties and states and is urging law enforcement agencies to take a look at their cold cases.

While Keen is already back to working on solving more crimes, he feels solving the Milam case will always be the highlight of his decades-long career.

“If I do nothing else, at least I did this."