Police have arrested 20 year-old New York City resident Jabrai Jordan Copney for the murder of Justin Cosby that occurred in the basement of Harvard’s Kirkland House, according to The Boston Globe. Copney, who is not a Harvard student, turned himself into police Thursday night. In a statement, prosecutors said they believed Cosby and Copney knew each other and that other people were involved in the confrontation as well.

The Harvard Crimson reported Thursday that Cosby may have been selling marijuana to students at the college. Police are investigating if that is the reason that he was in Kirkland House.