By Dan Whitcomb

LOS ANGELES (Reuters) - A 16-year-old boy was charged with murder on Friday in connection with the killing of a police officer who was shot as he sat in his car outside his department's headquarters in the Los Angeles suburb of Downey, prosecutors said.

Abel Diaz was one of three people arrested in the death of Downey police officer Ricardo "Ricky" Galvez on Wednesday night following what authorities have described as a botched robbery.

A source close to the case told Reuters that Diaz was not believed to have been the suspect who actually shot Galvez but he was still charged with one count of murder for taking part in the robbery in which the officer was killed.

The two other suspects arrested, both adults, have not yet been charged or identified.

Diaz was expected to make an initial court appearance later on Friday afternoon and faces a maximum sentence of life in prison if convicted at trial. Prosecutors have asked that he be held in lieu of $1 million bail.

Galvez, 29, was sitting in his personal car outside the Downey Police Department on Wednesday night when, according to the Los Angeles County Sheriff's Department, the three suspects arrived and ran up to the vehicle.

Sheriff's Lieutenant John Corina said at a news conference earlier this week opened fire on the former U.S. Marine in the community 10 miles (16 km) southeast of downtown Los Angeles.

A fellow officer driving nearby heard the gunshots, saw a vehicle leaving the parking lot and gave chase, ultimately seeing the occupants of that vehicle ditch it in a residential area of neighboring Montebello before fleeing on foot, according to Corina.

Two adults and a juvenile were arrested during a search of the area, and police recovered a revolver believed to have been used in the shooting of Galvez.

Downey Police Chief Carl Charles has described Galvez to reporters as "a tremendous young man."





(Reporting by Dan Whitcomb; Editing by Sandra Maler)