Matthew Muller, who is currently serving a 40-year sentence for the kidnapping of Denise Huskins, pled guilty Friday in Santa Clara County court on new charges of medicating and then sexually assaulting another woman.

Muller was in prison for the infamous Vallejo kidnapping when he implicated himself in unsolved attacks in Palo Alto and Mountain View, prompting a renewed investigation and DNA analysis.

Convicted "American Nightmare" kidnapper and rapist Matthew Muller will appear in a San Jose courtroom on Friday. Muller was responsible for the 2015 kidnapping and sexual assault of a Northern California woman.

The case Muller is most known for, as shown in Netflix’s ‘American Nightmare,' happened in Vallejo in March 2015 and involved the kidnapping of Denise Huskins.

Matthew Muller was convicted of kidnapping and sexual assault in a 2015 case in which Vallejo police initially accused the victim and her boyfriend of making up the story of her abduction. He pleaded guilty this week in two additional cases.

"American Nightmare" victims Denise Huskins and Aaron Quinn worked with two small-town law enforcement officials to get kidnapper Matthew Muller to confess to more cold case crimes.

Muller was in prison for the infamous Vallejo kidnapping when he implicated himself in unsolved attacks in Palo Alto and Mountain View, prompting a renewed investigation and DNA analysis.

Muller admitted he committed two home invasions in 2009--one in Palo Alto and one in Mountain View. During those home invasions, Muller held captive, interrogated and threatened to rape two women.