A New York City police detective was convicted of manslaughter on Thursday, three years after he struck and killed a 66-year-old woman as she crossed a street in the Bronx.

Early on Oct. 30, 2009, Detective Kevin C. Spellman, a 22-year veteran of the Police Department, was driving south on Kingsbridge Avenue near West 232nd Street when he struck the woman, Drana Nikac, 66, as she crossed the avenue.

“The jury heard testimony that more than five hours after the incident Spellman’s blood alcohol level was nearly three times higher than the legal limit,” according to a statement from the office of the Bronx district attorney, Robert T. Johnson. “Witnesses also testified that the traffic light was red when Spellman’s car approached the intersection and struck the victim. Other evidence examined by the jury included beer cans found in the defendant’s vehicle as well as the presence of the defendant’s DNA on one of the open cans.”

But Mr. Spellman’s lawyer, Peter Brill, argued that the equipment used to test Detective Spellman’s blood was faulty. That was one of several factors that led the jury to acquit Detective Spellman of several more serious charges, including aggravated vehicular homicide and first-degree vehicular manslaughter, Mr. Brill said.