It took nearly two decades, but the trail of blood down the stairs outside a Manhattan apartment where a social worker was stabbed to death in 1993 led to a man the authorities say was the killer.

Early on Aug. 15, 1993, the police found James Hawkins’s naked body on the floor of his fourth-floor walk-up in Chelsea. Mr. Hawkins, 50, had been stabbed 25 times in the neck, chest and abdomen. Neighbors described him as a kind and gentle man whom they frequently heard signing arias.

Detectives scoured the walls for fingerprints. Tests showed that the blood on the stairs between Mr. Hawkins’s apartment and the building’s front door was not his. But the investigation ran out of leads and was closed. By 2010, changes in DNA technology and state laws led to a major new clue, and cold-case investigators from the Police Department and the office of the Manhattan district attorney, Cyrus R. Vance Jr., reopened the case.

On Wednesday, those investigators led Gordon Francis, 54, into a courtroom in State Supreme Court in Manhattan, where he was formally charged with murdering Mr. Hawkins.