The New York Police Department recently released security camera footage of a suspect wanted in the Manhattan shooting of Brandon Lincoln Woodward.

The footage shows the gunman exit the passenger side of a parked Lincoln sedan about 10 minutes before the shooting on Monday. The suspect was wearing khakis and a dark hooded sweatshirt and his face was not clearly captured on video. A separate photo shows the gunman reaching into his pocket for a pistol moments before he shot the 31-year-old from Los Angeles in the back of the head.

Authorities have begun to look into Woodward’s past to find a motive for the murder and clues to who the suspect might be. Detectives are investigating his possible involvement in the drug trade. According to records, Woodard has approximately 20 prior arrests in California, stretching back to 2004. Those arrests include drug charges, battery, grant theft, robbery and petty theft.

The slaying “was not a random thing as far as we can tell,” Mayor Michael Bloomberg said Tuesday.

Though the murder happened on the heavily trafficked West 58th Street near the Time Warner Center, so far no witnesses have come forth with information.

Woodward graduated in 2003 from Loyola Marymount University in Los Angeles with a bachelor’s degree in business administration. He identified himself as a law school student in a 2004 interview, attended Whittier Law School from fall of 2010 to Spring 2011, and most recently enrolled in University of West Los Angeles Law School. He had law school identification on him when he was killed, police told ABC News.