Three alleged gang members and one of their girlfriends faced federal charges Thursday after an off-duty Los Angeles Police Department officer was shot dead earlier this week. 

Fernando Arroyos, 27, was killed Monday night in South Los Angeles during an attempted robbery while he was looking at houses with his girlfriend, authorities said. 

Charged with violent crime in aid of racketeering were suspects Luis Alfredo De La Rosa Rios, 29; Ernesto Cisneros, 22; Jesse Contreras, 34; and Rio’s girlfriend Haylee Marie Grisham, 18, according to the U.S. Justice Department. 

They could face the death penalty if convicted. 

Los Angeles police Officer Fernando Arroyos, 27, was killed Monday night while house hunting with his girlfriend. 

Los Angeles police Officer Fernando Arroyos, 27, was killed Monday night while house hunting with his girlfriend.  (Los Angeles Police Protective League)

LOS ANGELES OFF-DUTY POLICE OFFICER SHOT DEAD WHILE HOUSE HUNTING WITH GIRLFRIEND; 4 ARRESTED 

The suspects drove up to the house Arroyos and his girlfriend were looking at Monday night and Rios and Cisneros robbed them at gunpoint, the Justice Department release said.

Memorial photo of LA officer Fernando Arroyos

Memorial photo of Los Angeles police Officer Fernando Arroyos (Los Angeles Police Protective League)

Arroyos reportedly exchanged gunfire with one of the suspects and was hit once. He collapsed in an alley and later died at a hospital. 

The suspects allegedly fled after Arroyos was hit. 

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Investigators have surveillance video of the suspects going to another home after the shooting, according to the release. 

Fox News' Louis Casiano contributed to this report.