"This case was solved with the use of DNA and, specifically, DNA genealogy," Adams said. "And, quite honestly, without that, I don't know that we would have ever solved it."
The authorities did not share a motive, but evidence at the scene suggested it was related not to a robbery but possibly to a sex crime. Adams said Biechler was found with her jeans unbuttoned with the zipper down, exposing her underwear, which contained Sinopoli's semen.
The case joins a catalogue of others in recent years that have been solved through DNA testing, a powerful tool in courtrooms across the country that has both led to people being exonerated of wrongful convictions and helped investigators find the killers in cold cases from decades ago.
Biechler's case was the oldest unsolved homicide investigation in Lancaster County, Adams said, underscoring the years of futile efforts and faulty leads that left investigators confounded by the mystery surrounding her killing. Dozens of people had been cleared in the case through blood-type tests, DNA examinations or other evidence.
"Lindy Sue Biechler was on the minds of many throughout the years," Adams said. "Certainly, law enforcement has never forgotten about her."
None of the tips that investigators received mentioned Sinopoli, who Adams said continued to live in the Lancaster County area since the killing. PennLive.com reported Sinopoli had worked as a press operator for more than 40 years.
On the day Biechler was killed, she travelled from the flower shop where she worked to her husband's workplace to get his paycheck, which she would deposit in a bank later that afternoon. Then she shopped for groceries.
Her aunt and uncle arrived at her apartment at 8.46pm, indicating she was killed in a two-hour window when no one else was home, police said.
DNA profile obtained in 1997
In 1997, investigators submitted the underwear worn by Biechler at the time of her death to a DNA lab, which confirmed that it contained semen, and then uploaded the DNA profile to CODIS, a national DNA database maintained by the FBI.
But investigators never received a match through CODIS.
Dan Krane, a professor of biology at Wright State University in Dayton, Ohio, who has researched tools to evaluate DNA evidence for criminal investigations, said that in 1997, "CODIS was still very young", with only about 2 million people in the database, compared with roughly 14 million today.
Most of the DNA in the database comes from criminal offenders or people who have been arrested and had their DNA collected, Krane said.
In December 2020, Cece Moore, a genetic genealogist who works with Parabon NanoLabs, a Virginia company whose services include novel DNA-based forensics, was given a DNA sample from the crime scene by the authorities.
The DNA tests from the person showed he had many recent immigrant family members from Italy.
Moore found there were about 2300 residents of Italian ancestry living in the area at the time of Biechler's death. From there, she further narrowed the pool of potential suspects to those whose ancestors had lived in Gasperina, Italy.
Then, using newspaper archives, public search databases, social media, court records and other resources, Moore determined Sinopoli, who has Italian ancestry, was a possible suspect, in part because he had lived in the same apartment building that Biechler had. She said at the news conference that she had later submitted a "highly scientific tip" to authorities.
'It's very meaningful to us'
Investigators surveilled Sinopoli, eventually following him into the airport. There, they retrieved a coffee cup that he had discarded.
Krane said that sort of strategy has been common among investigators for at least 20 years.
"I've heard a number of instances where the person being questioned was questioned for hours and hours, but as soon as they accepted a drink and drank from it, the questioning was over, and they were allowed to leave," he said.
On Monday, authorities said they had informed Biechler's husband of Sinopoli's arrest.
"It's very meaningful to us," Adams said, "to be able to provide some sense of relief to the victims."
This article originally appeared in The New York Times.
Written by: Eduardo Medina
© 2022 THE NEW YORK TIMES