Authorities in Philadelphia have issued an arrest warrant for Bill Cosby, after prosecutors there formally charged him on Wednesday with drugging and sexually assaulting former Temple employee Andrea Constand.

The New York Times reports the alleged incident took place at the "Cosby Show" dad's Elkins Park home in January 2004. Constand was not made available for comment during Wednesday's press conference, where newly elected District Attorney Kevin Steele announced the charge.

Prosecutors characterized the evidence they have against Cosby as "strong" and insisted he got close to his alleged victim by presenting himself as a mentor to her.

According to Fox News, Cosby now formally faces aggravated indecent assault charges and is expected to surrender to authorities later today to face arraignment.

In all, more than 50 women have recently stepped forward to claim they were drugged and sexually assaulted by the now 78-year-old Cosby over a period that spans more than five decades staring in the 1960s.

Cosby recently filed defamation suits against several of his accusers, including former supermodel Beverly Johnson.

In the Constand case, Cosby previously conceded that the two were intimate, but insisted it was consensual, even though Constand argued she was in a relationship with a woman at the time of the incident.

People magazine reports she later characterized the famed comedian as a "narcissist," claiming he missed several hints that she was gay.

Last summer, outgoing Montgomery County District Attorney Risa Vetri Ferman quietly reopened Constand's case, sending detectives to Canada to re-interview her, while Steele oversaw the investigation.

Before now, Cosby was never criminally charged in connection with any of the cases and has long proclaimed his innocence.

Constand also recently filed a defamation suit against Cosby over comments he made after she went public with her allegations. 

The two previously settled a civil suit she filed against him, which also included a strict confidentiality agreement that she is now trying to undo. 

Constand was operations manager of the Temple University women's basketball team when she first met Cosby in November 2002. The civil suit claimed in early 2004, Cosby invited Constand to his mansion under the pretense he wanted to help her with her plan to seek a different career.

Once there, she insisted he offered her an assortment of blue pills he claimed would help her relax. While "semi-conscious" she contended Cosby sexually assaulted her as she completely lost consciousness.