A suspect in the killing of a 27-year-old Pennsylvania woman nearly 30 years ago has been arrested, and a pair of yellow socks helped break open the cold case, investigators said.

Theodore Dill Donahue, now 52, was arrested Tuesday in the 1991 murder of his girlfriend, Denise Sharon Kulb, after an extensive reexamination of the case, Philadelphia prosecutors and state police announced.

Kulb’s body was discovered on Nov. 12, 1991, in a wooded area of an undeveloped cul-de-sac in Delaware County.

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She was clothed in only a sweater with other clothes piled on top, including pants, a jacket and one yellow sock, The Philadelphia Inquirer reported.

Days after finding Kulb’s body, investigators searched Donahue’s apartment and found one yellow sock that matched the one with the body, the paper reported. But investigators said they weren't able to link the socks at the time.

When they started reexamining the case in 2015 with new investigative tools, they were able to connect the separated socks using photo-enhancing technology, Fox 29 Philadelphia reported. The yellow socks, along with witness interviews and changes in Donahue's accounts over the years, helped lead to an arrest, officials said.

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Donahue was charged with murder, abuse of a corpse, evidence tampering, obstruction and false reports to police, officials said.

“He’s not guilty. He denies the charges, and we will dispute it in court,” Donahue’s attorney, R. Emmett Madden, said during a brief phone conversation, The Inquirer reported.

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Anthony Voci, a supervisor of the district attorney's homicide unit, said he was confident in his office’s chances of getting a conviction despite the passage of nearly three decades.

“Sometimes cases get better with time, just like wine does,” he said.

The Associated Press contributed to this report.