Prosecutors have now officially charged David Merck for violently attacking "NCIS" actress Pauley Perrette outside her home in the Hollywood Hills on Thursday. He has pleaded not guilty to the charges.

According to the Los Angeles Times, Merck, a 45-year-old homeless man, was charged with felony criminal threats and imprisonment by violence for allegedly attacking Perrette in front of her home on Cahuenga Terrace in the Hollywood Hills neighborhood of LA.

During his arraignment on Monday, he pleaded not guilty. If he is convicted of the crime, he faces up to 4 years in jail.

Los Angeles Police Sgt. Bob Ward spoke with the LA Times and said that Merck is no stranger to crime. Following the defendant's plea, Ward said Merck has an extensive record of criminal history.

Perrette was able to work with the authorities to render a police sketch of her attacker. A friend of the actress took a picture of the sketch and started looking for the suspect on his own. The friend ended up locating the man and called the police, who came to a nearby 7-Eleven on the corner of Cahuenga Boulevard and Yucca Street to arrest the man for the assault.

Perrette took to social media later that night, after the attack, and posted about the incident with graphic detail. She posted a picture of a document that detailed the attack on Twitter and has since received an outpouring of support from the community.

She said the man repeatedly beat her and tried to drag her into a an empty garage nearby. She added that she tried to appeal to the man's better nature, but was met with punches to the face, before he eventually let her go.

Perrette, who plays forensic scientist Abby Sciuto on "NCIS," is a known advocate for the homeless.