Montgomery County police said they believe multiple participants were involved in what was likely the targeted killing of a District middle school principal.

A vehicle was seen pulling out of the alley behind Shaw Middle School principal Brian Betts’ Silver Spring house around 12:15 a.m. on April 15, police said Thursday. Betts was found shot to death around 7:30 p.m. that day. He was last heard from around 11:30 p.m. April 14, when he placed a phone call.