(KRON) -- Matthew Muller, the notorious rapist who was convicted of kidnapping Denise Huskins in Vallejo, pleaded guilty on Friday to victimizing more women in the South Bay. Muller, 47, was featured in a Netflix documentary, "American Nightmare," that chronicled Huskins’ harrowing experience in 2015 when Muller broke into her home, kidnapped and raped her, and held her for two days inside his South Lake Tahoe cabin. On Friday, Muller pleaded guilty to sexually assaulting women during a pair of home invasions in Mountain View and Palo Alto 15 years ago. He will face life in prison when he is sentenced on February 21 in the Santa Clara County courthouse. "This extremely dangerous person left a trail of traumatized and terrified victims," District Attorney Jeff Rosen said. "It took the collective courage of his victims and determined law enforcement officers to stop him. This nightmare is over." Denise Huskins arrives at the 2024 Critics Choice Real TV Awards on June 15, 2024 in Los Angeles. (Photo by Steve Granitz/FilmMagic) On Sept. 29, 2009, Muller broke into a woman’s Mountain View home, attacked her, tied her up, made her drink a concoction of medications, and said he was going to rape her. After the victim persuaded him against it, he told the victim to get a dog for protection and fled.  On Oct. 18, 2009, Muller broke into a Palo Alto home, bound and gagged a woman in her 30’s and made her drink Nyquil. He sexually assaulted her until she also persuaded him to stop. Muller gave the victim crime prevention advice and fled. Matthew Muller confessed to South Bay cold cases: court documents On March 23, 2015, Muller broke into a Vallejo home, where he drugged, and tied up a young couple. He kidnapped Huskins, brought her to his cabin in South Lake Tahoe, and recorded videos of rapes. Two days later, Muller drove Huskins to Southern California and released her. Muller was arrested in June of 2015 for both the Vallejo kidnapping and a violent Dublin home invasion.  Denise Huskins (right) and her husband, Aaron Quinn, appear at a law enforcement training event in Seaside in March 2024. (KRON4 / Amy Larson) Muller pleaded guilty in 2016 for the Huskins case and was sentenced to serve decades in a federal prison. Following his guilty plea in Santa Clara County this week, the serial predator will now face kidnapping for ransom charges in Contra Costa County. The investigation into Muller was reopened earlier this year when Seaside Police Chief Nick Borges teamed up with Huskins. Borges said he had never heard of the unsolved 2009 South Bay cold cases until he watched "American Nightmare." Chief Borges began sending letters to Muller, who was an inmate at a federal prison in Arizona. How Denise Huskins helped find more victims of ‘American Nightmare’ kidnapper Borges received reply letters from Muller in which he confessed to victimizing Huskins in Vallejo, as well as a woman in Palo Alto, and a third woman in Mountain View, court documents obtained by KRON4 show. In one prison letter, Muller explained why he first began breaking into the homes of young women, court documents state. His criminal life began with voyeurism. Over time, it escalated into home invasions, attempted rapes, and kidnapping. "The idea to raid a home and rape a woman developed in August or September 2009 and he was in a manic state,” court documents state. Muller served as a Marine, graduated from Harvard University, and worked as an attorney in California. Investigators described him as "exceptionally intelligent." He meticulously planned out his crimes and practiced before "terrorizing" victims who were woken up in the middle of the night by a home intruder, investigators said. Denise Huskins talks to reporters in Seaside, Calif. on Jan. 7, 2025. (KRON4 Photo) In another prison letter, Muller described "how it’s strange that he used to protect and enable women, and was somehow driven to hurt them instead." In addition to the prison letter confessions, advances in DNA technology allowed cold case investigators to make a DNA match from evidence found at the Palo Alto crime scene. Muller’s DNA was detected on one of the bindings that was used to tie the victim up, Rosen said. Timeline: Matthew Muller and the ‘American Nightmare’ case Huskins spoke to reporters at a news conference earlier this month. "This man had all the markers of a serial predator. It’s something he crafted and perfected over a long period of time. This is just the tip of the iceberg," she said. Tears flowed down Huskins’ face as she talked about finding more victims whom were previously unknown to law enforcement, and helping them seek justice. Borges said Huskins is not only a survivor, she's a hero for seeking justice beyond her case.