The NCIS star was left fearing for her life on Thursday (12Nov15) after she was targeted by a "psychotic homeless man" who brutally assaulted her and threatened to kill her.

She talked herself out of danger and walked free, before reporting the incident to police and helping them track down the suspect by drawing a sketch of her attacker, which led cops to arrest David Merck.

The 45 year old has since been arraigned on a felony of making a criminal threat and a second charge of false imprisonment by violence.

He is currently being held on $60,000 (£37,500) bail, and if convicted, Merck could be handed up to four years in prison, reports TMZ.com.

The actress, an outspoken civil rights activist, took to Twitter.com in the hours after Thursday's terrifying incident and detailed the violent act for fans, admitting the encounter had left her "shaken and traumatized".

"On my street, I was jumped by a very psychotic homeless man..." she recalled. "He grabbed me so forcefully, pinned my arm, punched me in the nose (and) forehead repeatedly telling me he was going to kill me.

"Then he showed me how he was going to kill me. He kept repeating his name... 'I'm going to kill you'. I was alone, terrified and trapped... There was an empty garage behind me and I knew if he got me in there I was dead... I knew I couldn't overcome him. He started to punch me again, and then said: 'Get the f**k out of here'. And I did. I went into shock. Collapsed on the sidewalk."

However, Perrette insisted the attack only highlighted the need to do more to help the homeless and mentally ill.

"I am shaken and traumatized...," she continued. "My house, my beloved Hollywood... My beloved homeless people that I spend my life protecting... My life changed tonight. We need full mental health care. We need housing and help for the homeless. We need to support our cops. We need to not walk alone. I need to heal... I almost died tonight."