LOS ANGELES — A serial killer known as the ‘‘Grim Sleeper’’ was sentenced to death Wednesday for the murders of nine women and a teenage girl that went unsolved for years as the body count grew in a poor section of Los Angeles haunted by the scourge of crack cocaine.

Lonnie Franklin Jr. was sentenced in Los Angeles County Superior Court after family members of his victims spoke about the pain they had endured for decades.

‘‘I can’t think of anyone I’ve encountered in all my years in the criminal justice system that has committed the monstrous crimes that you have,’’ Judge Kathleen Kennedy told Franklin.

The killings occurred over more than two decades during the crack epidemic, and community members complained that police didn’t investigate because the victims were black and poor, many of them drug users and prostitutes.

Franklin, 63, a former trash collector and onetime garage attendant for Los Angeles police, denied any role in the killings to investigators but didn’t utter a word in his defense during his lengthy trial.

Prosecutors connected him to the crimes through DNA, ballistics, photos, and the words of the sole known survivor, who managed to get away after being shot. A Polaroid photo of her partly nude and bleeding from her wound was found in Franklin’s garage.

The killer earned his moniker because police once theorized that during stretches of time without a reported slaying, he was perhaps in prison for other crimes or laying low.

Associated Press