Law enforcement officers from throughout California will honor a Riverside police officer Wednesday who was shot and killed in an ambush Thursday at a stoplight -- one of four slayings connected to a revenge plot involving a former LAPD officer.

Riverside Chief Sergio Diaz, military veterans, colleagues and family members will attend the memorial for Officer Michael Crain at Grove Community Church. The 34-year-old father of two - a Marine and 11-year veteran of Riverside PD -- was killed Thursday morning when he and a trainee were waiting at a stoplight in Riverside.

The slaying is one of four connected to former ex-LAPD officer Christopher Dorner, who was involved in a shootout that ended with a cabin fire Tuesday in the Big Bear area. Forensics experts will determine whether charred remains in the cabin are those of Dorner.