A Los Angeles County grand jury has charged a convicted serial killer with three more murders.

Authorities Thursday said Michael Hughes was indicted last week on charges that he raped, sodomized and strangled a 15-year-old girl, whose body was found in an Inglewood park in 1986. He has also been charged with killing two women in Los Angeles in 1986 and 1993. One body was found in a school stairwell.

Authorities say Hughes, 53, was linked to the crimes by DNA evidence.

He pleaded not guilty to the new charges on Tuesday and could face the death penalty if convicted.

Hughes already is serving a life term without chance of parole for killing four women in 1992 and 1993.