LOS ANGELES » After a months-long investigation, Los Angeles police arrested a county sheriff’s deputy who is suspected in the shooting death of a man in Sylmar last June.

Seventeen-year veteran Francisco Gamez, 41, was taken into custody Wednesday and held on suspicion of murder, attempted murder and use of a firearm during the commission of a felony, sheriff’s officials said.

"The off-duty acts that led to the arrest of Francisco Gamez are deeply disturbing to me and to the entire Los Angeles County Sheriff’s Department," Sheriff Lee Baca said in a statement Wednesday.

Just after 11 a.m. on June 17, patrol officers were flagged down in a residential area of Sylmar after 38-year-old Armando Casillas was gunned down. He was pronounced dead after being taken to Providence Holy Cross Hospital.

The assailant also shot at a second victim who was not injured.

LAPD Officer Venus Hall said details about the nature of the incident were not being released Wednesday.

The district attorney’s office had not yet received a filing from LAPD detectives requesting formal charges.

Gamez was being held in lieu of $4 million bail at the 77th Street Jail. Neither the sheriff’s office nor LAPD knew if he had a lawyer who could be reached for comment.

Gamez had been assigned to the West Hollywood station since 2005. He was relieved of duty with pay on July 3. Sheriff’s spokesman Steve Whitmore said proceedings would begin Thursday to stop Gamez’s pay, and termination was likely.