NEW YORK (AP) — A Manhattan man killed his roommate before trying to dispose of his body in the ocean, prosecutors said.

New York City prosecutors have charged the man in the brutal stabbing, which they say was followed by an attempt to cut up and dispose of the body.

Christian Millet, 23, was arraigned on Thursday. He is being held on murder charges without bail. A telephone message was left seeking comment with the public defender listed in his case, attorney Shari Leigh Vrod.

The investigation started on Feb. 5, when police in the NYPD harbor boat unit found body parts, including a severed torso, in a duffel bag floating in the East River.

Police eventually identified the body, including a severed torso, as the remains of Edwin Echevarria, 65.

In court documents, prosecutors said Millet confessed to stabbing Echevarria. They said investigators found blood-soaked paper towels in a closet apartment, along with a potential murder weapon, a screwdriver with a sharp, cylindrical head.

At an arraignment hearing on Thursday, prosecutors described Echevarria as a “grandfather figure” in Millet’s life, according to a report from the New York Times. But prosecutors said at the hearing that Millet confessed to killing the man after “an insane urge to kill.”