Alleged serial killer charged Thursday in 1993 slaying of Illinois teen

(CBS/WBBM) GLENVIEW, Ill. - A man awaiting trial in California for allegedly killing two women was charged Thursday in the 1993 stabbing death of a teenage Illinois girl.

Pictures: Serial Killer's Victims?

Cook County State's Attorney Anita Alvarez announced that alleged serial killer Michael Gargiulo was charged today with brutally stabbing to death Tricia Pacaccio 18 years ago on the doorstep of her home, reports CBS station WBBM.

The 18-year-old's father found her body on Aug. 14, 1993, reports WBBM. According to the Cook County sheriff's office, she had been stabbed 12 times.

Gargiulo had already pleaded not guilty in Los Angeles in 2008 to murdering Ashley Ellerin and Maria Bruno as well as attempting to kill another woman, Michelle Murphy, but police say they believe Pacaccio was his first victim.

At the time of Pacaccio's murder, Gargiulo was reportedly a high school junior who lived in the same neighborhood as the victim.

Although Gargiulo's DNA was reportedly found on the victim's fingers he was never charged with the crime.

The victim's parents, Rick and Diane Pacaccio told WBBM that they blamed Cook County prosecutors for dropping the ball in the case.

"My daughter's case is not going to go unsolved," Rick Pacaccio said. "It's not going to be put on a shelf."

An old friend of Gargiulo, Scott Olson, reportedly said the man had a "crazy switch" that Gargiulo's own parents feared.

The big break in the case came in May, after an episode of 48 Hours Mystery special led to a new witness and new information in the case.

48 Hours Mystery recently reported on the Michael Gargiulo case