After an investigation that spanned more than two decades, officials announced Thursday they have found the man they believe murdered 21-year-old Lena Bruce in 1992.

DNA evidence led investigators to James Witkowski, 42, of Dorchester, Suffolk County District Attorney Dan Conley said Thursday afternoon in a press conference. Witkowski will be arraigned at a to-be-determined date.

Detectives collected samples from Bruce’s body that had been stored and preserved for nearly a quarter century, Conley said. The evidence was a match with a sample collected from Witkowski while the man was serving a sentence for a parole violation on felony charges, Conley said.

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Bruce’s death, which attracted wide media coverage in Boston and Philadelphia, stumped “generations of investigators,” Conley said.

Advances in DNA technology and a policy of collecting DNA swabs from prisoners with felony convictions were to thank for finally cracking the case, he added.

“As a result, we have today what they could not have imagined in 1992,” Conley said.

Boston Police Commissioner William Evans said the department continues to work on cold cases and urged witnesses to come forward.

“We never forget,” Evans said.

Bruce, a 21-year-old Philadelphia native, was found dead in her South End home in 1992, after it appeared she had been strangled and sexually assaulted.

At the time, she was the only black woman in her class of nearly 250 students at Tufts University to graduate with an electrical engineering degree, officials said, and she had recently been offered a job with a prominent city firm. It was her roommate who discovered her body after returning from a weekend trip.

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Her sorority sisters at the Xi Tau chapter of Delta Sigma Theta have paid tribute to Bruce by holding annual candle light vigils and raising awareness about violence against women. The chapter awards a scholarship in her memory every year to support young women of limited means.

“In every way, Lena Bruce was the very kind of person we want in our city,” Conley said. “Had she been allowed to grow into a successful woman, there’s no telling what she could have accomplished.”

At the press conference, Conley also called for an expansion of the state’s DNA database, and touted laws in other states like Virginia, which require that police collect DNA swabs after arrests.

There are currently 3,000 pieces of DNA evidence in storage at the Boston Police Department’s crime lab, said Don Hayes, the lab’s director, speaking to reporters. Of those, about 1,800 of those samples have been linked to suspects and 1,200 remain unmatched, he said.