8:15 AM PT -- Police arrested the suspect ... a 45-year-old man named David Merck, and booked him for felony battery. ET got Pauley's sketch of Merck, and a photo one of her friends later took of him.
She could have a future in forensic art.
Pauley Perrette, who plays scientist Abby Sciuto on "NCIS," says a "psychotic homeless man" punched her in the face Thursday night and vowed he would kill her.
Perrette says she was walking from her Hollywood home to a guest house she owned when the guy appeared, repeatedly threatening to end her life.
It's a bizarre story. Perrette says she told the guy, who called himself William, that he had a "beautiful name" but he just unloaded and punched her again.
She says, "I went into shock ... collapsed on the sidewalk." She says cops came, she drew a "police sketch" of the guy, who was "headed towards Hollywood Blvd with murder in his eyes." Perrette says cops arrested him.
Now it gets really weird. Perrette tweeted, "I am shaken and traumatized. My house, my beloved Hollywood. My beloved homeless people that I spend my life protecting ... My life changed tonight."
She ends by writing, "We need to not walk alone. I need to heal. I almost died tonight."