SAN FERNANDO (CBS) — Prosecutors leveled five more charges Wednesday against a 19-year-old man they said had sex with underage girls he met on Facebook.

Michael Downs, a resident of Santa Clarita, is set to be arraigned Feb. 6 in San Fernando Superior Court on 34 counts, including the new felony charges of committing a lewd act on a child, unlawful sexual intercourse, sexual penetration by a foreign object and misdemeanor sexual battery.

The new charges involving three youths who were between 13 and 15 years old, brings to 15 the number of alleged victims, according to Jane Robison of the District Attorney’s Office.

Downs was already charged with sex-related crimes — including committing a lewd act on a child, unlawful sexual intercourse and oral copulation of a person under 18 — involving a dozen other girls who were between 12 and 16 years old.

Downs met the girls at social events, public places and through  Facebook throughout 2011, said Lt. Carlos Marquez of the sheriff’s Special Victims Bureau.

The assaults occurred at various locations throughout the Santa Clarita Valley, according to the sheriff’s lieutenant.

“His alleged approach was befriending victims on Facebook by claiming he was 16 years old and gaining their confidence in part by giving the names of other teen girls and saying he was friends with them,” Marquez said. “He would ultimately convince them to meet with him and then allegedly had sex with them.”

(©2012 CBS Local Media, a division of CBS Radio Inc. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. Wire services contributed to this report.)