BAY SHORE, N.Y. — The police came to the door two days after Irene Wilkowitz’s sister went missing.

Her father answered. Wilkowitz, 17 at the time and too frightened to hear what the officer might say, began climbing the stairs to her room. But the officer stopped her. “You have to stay and hear this,” he said.

“We found her,” he told them. A splash of relief struck Wilkowitz. Then the officer clarified: “We found her body.”

Hours earlier, on March 25, 1980, a woman had noticed a barefoot figure lying on a neighbor’s lawn a few miles away in Bay Shore. It was Eve Wilkowitz. She’d last been seen boarding a late-night Long Island Rail Road train from Penn Station in Manhattan, where she worked as a secretary at a publishing house.

Sometime during her journey home, she’d been kidnapped, bound, raped, strangled and dumped. She was 20.

Eve Wilkowitz was 20 when she was murdered in 1980. Kayana Szymczak / for NBC News

Wilkowitz remembers watching, numb, as her father wept, and driving with him to the morgue to identify Eve’s body. They returned to a crush of news cameras. Then, they grieved and waited for police to catch the killer.

“I was scared out of my mind,” Wilkowitz recalled. “I kept thinking, and I kept saying, ‘Well, if it happened to her, I could be next.’”

That fear didn’t fade.

A long, sweeping investigation failed to produce a suspect. Police reopened the case several times over the years, hoping that a fresh set of eyes or advanced forensic techniques would pry loose new clues in what one local detective described as “one of the biggest mystery murders we’ve ever had.”

The original investigation of Eve Wilkowitz's killing lasted years. It's been reopened several times since. Kayana Szymczak / for NBC News

Today, they are no closer to Eve’s killer than they were the morning she was found. Wilkowitz, 57 and Eve’s only living close relative, has pressed investigators to try a new option: investigative genetic genealogy, a revolutionary — and divisive — tool that has been used to crack dozens of cold cases across America in the past 18 months. It would enable police to submit the killer’s DNA, found in semen left on her sister’s body, to consumer DNA databases, which contain DNA profiles of tens of thousands of people who are not in criminal databases. The move could increase the chances of finding a relative of the killer ─ and, ultimately, the killer himself.

But New York health officials won’t let investigators do so.

Because public crime laboratories aren’t equipped to do the advanced DNA analysis required of the newly popular technique, law enforcement authorities must seek help from private laboratories, which are regulated by the New York State Department of Health. Under a decades-old regulation from a time when DNA analysis first became common in criminal cases, private labs are required to obtain permits before they can do such forensics work in New York.

No private lab has this permit for investigative genetic genealogy. That has left New York authorities unable to join the national rush of law enforcement agencies using investigative genetic genealogy to reexamine decades-old murders and rapes.

“It’s definitely frustrating,” said Suffolk County Police Lt. Kevin Beyrer, a homicide investigator who keeps the Eve Wilkowitz murder file ─ three bankers-boxes stuffed with yellowed typewritten reports, photographs and newspaper clippings ─ in his office. “The technology’s there. Other states have used it. Other states have been successful in it. This is a case that’s almost screaming for it.”