Police say a New Jersey man who fired shots inside a mall last year before killing himself was under investigation for selling drugs.

Hackensack police released the information about Richard Shoop on Tuesday along with details of a large-scale drug sweep in northern New Jersey.

Investigators say Shoop had sold MDMA to an undercover officer 10 days before he opened fire inside the Garden State Plaza in Paramus last November. No one else was hurt.

Police say a note found after the shooting indicated Shoop knew he was under investigation.

Hackensack Police Director Michael Mordaga says Shoop had also been arrested six months earlier for selling the pure form of ecstasy, known as "Molly."

Authorities say they arrested more than 160 suspected drug dealers as part of the seven-month investigation.