Wearing dark glasses, Darryl Littlejohn looked straight ahead as the first-degree murder verdict was read after about six hours of jury deliberations.
The 44-year-old parolee faces up to life in prison without parole in the 2006 death of criminal justice student Imette St. Guillen of Boston.
His sentencing is set for July 8; Littlejohn is already serving 25 years to life for kidnapping another woman.
St. Guillen's mother, Maureen, and sister, Alejandra, hugged each other and wept as they heard the verdict.
"With Imette's death, all of our lives are forever darkened," Maureen St. Guillen said in a statement she read outside the courtroom. "A little piece of us died with her."
Defense lawyer Joyce David said Littlejohn planned to appeal.
"I hope the family gets some closure from this, but I believe they have the wrong man," said David, who argued that Littlejohn was framed.
Capping a night out, St. Guillen went to a bar called The Falls early on Feb. 24, 2006. The establishment is owned by the same family who ran Dorrian's Red Hand, the tavern where "preppie killer" Robert Chambers met Jennifer Levin before strangling her during rough sex in the 1980s — a connection Littlejohn's lawyers emphasized in his trial.
St. Guillen stayed at The Falls past closing. Witnesses said she was asked to leave, and Littlejohn escorted her out.
Later that day, St. Guillen's body was found wrapped in a quilt along a desolate road in Brooklyn. She was bound and gagged, and had been beaten and sexually assaulted before being asphyxiated. The sexual assault was a factor in the first-degree murder conviction.
The nature of her abuse was eerily similar to attacks on two other women who say Littlejohn attacked them, but they lived through it, prosecutor Kenneth Taub told jurors. Littlejohn was charged — and convicted — in only one of those attacks, but both women testified during his trial in St. Guillen's death.
Both said a stocky man in fatigues stopped them on New York City streets in 2005, demanded their IDs, handcuffed them and abducted them. One woman escaped; the other was blindfolded, sexually assaulted and eventually released.
In his closing statement, Taub said Littlejohn killed St. Guillen because she could implicate him.
"If he let her live, she would wake up sober the next morning and say, 'The guy that raped me is the guy who threw me out of the bar,"' Taub said.
Prosecutors portrayed Littlejohn as a sexual predator with a propensity for pretending he was a law enforcement officer. But David pinned the slaying on the bar's manager, Danny Dorrian, and argued Littlejohn was framed in a cover-up designed to shield the Dorrian family and former Mayor Rudy Giuliani from scandal. Giuliani adviser Anthony Carbonetti has ties to the Dorrians.
David suggested Danny Dorrian accidentally killed St. Guillen after a night of sexual domination play. Taub called David's accusation "the rankest kind of speculation," and Dorrian denied in testimony having anything to do with St. Guillen's killing or concealing anything criminal.
But he acknowledged that because of his family's history with the Chambers case, he initially wasn't forthcoming with investigators about kicking out St. Guillen.
David said investigators zeroed in on Littlejohn because he had a lengthy criminal record.
St. Guillen's death was part of a string of incidents — including the July 2006 killing of another clubgoer, 18-year-old Jennifer Moore — that prompted scrutiny of nightlife safety.
In response, the city took steps to require security cameras at nightclub doors and make it easier to shut down businesses that sell fake identification. The city also boosted authorities' ability to make clubs prove their security staffers are licensed.
Club owners also agreed to back voluntary guidelines for improving security, including using scanning machines to record IDs and screening patrons for weapons.