He peeled off the trans-dermal patch that dispensed medication directly into his skin, and threw it out his car window as he drove.
Once in the city, he parked on the West Side - leaving his wallet in his car - and walked to the New York Waterway terminal at 39th Street and 12th Avenue.
There, unprovoked on a sunny July afternoon, he admittedly grabbed a 2-year-old boy named Thorin who lived nearby and happened to be playing with his plastic bicycle.
Then, when Thorin's terrified mother tried to stop him, he threw her to the concrete and choked her into unconsciousness, stopping only when two bystanders hoisted him off her.
"I begged, I begged, I begged," the hero mom, Jil Novenski, testified in tears yesterday - recounting her horror to a Manhattan judge in hopes that the psychotic stranger may be locked up forever.
"I screamed, 'Oh, God! Please, no!' I thought for sure he was going to kill me in front of my son. I wanted to make sure that if I was going to die, he wasn't going to get [Thorin.]
"He squeezed harder and harder," Novenski remembered of the stranger's hands around her throat. "Then, everything went black."
Amazingly, the psychotic shrink - child psychiatrist Dr. William Johns III - remains licensed to practice medicine in Florida, West Virginia and Hawaii, according to online records.
This, despite his having been in jail for the full year since admittedly attacking the woman and her son.
Johns quickly told cops he was Jesus Christ, trying to save the boy from some vague "danger."
"I tightened my grip on her when the two guys came over because I thought they might try to pull me off of her," he admitted, according to court documents.
Johns, who has a history of severe alcohol dependence, drunken driving, violence and stopping his medications, is now fighting to be freed so he can attend an outpatient psychiatric program near his hometown, Vero Beach.
He pleaded not guilty by reason of mental illness in April. Yesterday's hearing, which continues today, will determine if his next move is out the door or - as prosecutors and Novenski hope - into a locked psych facility.
"Otherwise, what are we waiting for?" Novenski, 39, told The Post yesterday. "He's going to kill somebody."