A Suburban Hospital boiler-room worker on Wednesday was convicted of first-degree murder in the stabbing of colleague on New Year’s Day.

Montgomery County prosecutors said that Keith Little hated Roosevelt Brockington, 40 his supervisor. Brockington was found in the boiler room office with 72 stab wounds and a 12-inch knife still embedded in his neck.

During a trial in Montgomery Circuit Court, prosecutors said Little had worked a second job at the federal courthouse in Greenbelt. That led to friction between the men when Brockington set Little’s hospital shift schedule in a way that made it impossible to keep the other job, they said.

People heard Little making threats directed toward Brockington, prosecutors said. And, on the evening of Jan. 5, a hospital co-worker saw Little washing something with chemically treated water, walked over and saw a pair of gloves and black ski mask that police say were used by the killer. Little told the worker not to worry and buried the items in a trash can, authorities said, where police later found them.

Little had also been accused of killing a co-worker at a previous job, at a maintenance facility in the District in 2003, but he was acquitted after a four-day jury trial.