MANASSAS, Va. — A convicted sex offender charged in the 1975 slayings of two sisters who vanished from a suburban Maryland mall now faces new charges in an unrelated case in northern Virginia.

Multiple news outlets report court records show a Manassas grand jury on Monday indicted Lloyd Lee Welch Jr. on charges of rape, sexual battery and indecent liberties in the sexual assault of a girl in Prince William County in 1996.

Welch is awaiting trial in Bedford County, Virginia, on charges of first-degree murder in the disappearance of 12-year-old Sheila Lyon and 10-year-old Katherine Lyon. The sisters were last seen walking from their house to the Wheaton Plaza Mall. They never returned, and no bodies were found.

Welch is currently serving a decades-long sentence for molesting a 10-year-old girl in Delaware.