Paul Wersicks, who several doctors assert was psychotic when he allegedly killed a man last July, had gone into psychotic states earlier in his life-once placing his pet cat in a container of battery acid-a psychiatrist testified yesterday at Wersick's murder trial.

Dr. Reginald Lourie told the jury that during that incident and others, including the shooting of Montgomery County assessor George Angerman Jr., Wersick felt everything "go in and out of focus."

Lourie was the fourth medical expert called by the defense to testify that 16-year-old Wersick, who has pleaded innocent by reason of insanity to the murder charge, was legally insane when the crime occurred.

Wersick told Lourie that in the moments before Angerman was shot in a Rockville garage things, "'went in and out of focus. . . and the next thing I knew I was hearing things around me and there was blood all over,'" the doctor testified yesterday.

But Lourie's testimony also focused on Wersick's upbringing, years when his mothers knew "he was different," when other children "picked on him" and Wersick began to "retreat" into a fantasy world.

When Wersick was about 4, he, like other preschoolers, had "imaginary companions," but Wersick's companions were Hitler and Mussolini, the doctor testified.

It was in those formative years that Wersick began to develop his primary and ongoing mental disorder, "a schizoid personality," which is a condition in which a person chooses to be a "loner" because he fears other people, Lourie stated.

Wersick's need to be cared for in those early years-normal for all children-were never left behind, and Wersick was still a 3-year-old in many ways, even at the time last year when Lourie interviewed him, the doctor said.

In one of those interviews, the youth told Lourie: "I feel inside like a crab without a shell, soft and defenseless. I was always that way'," Lourie testified yesterday.

At another point, the youth told him, "The world is full of people waiting to pull the trigger."

After testifying about Wersick's underlying mental disorders, Lourie told the jurors that last July 10, the day Angerman's murder occurred, Wersick had an argument with his mother, who had "grounded" him for a month because of a "shoplifting" incident.

Acting at the level of a 3-year-old, Wersick "gathered some materials to make somebody feel as bad. . . as degraded as he did," Lourie testified under cross-examination. With a boy scout neckerchief, a piece of rope and a gun, Wersick took a bus from his Wheaton home to Rockville, went to a parking garage and robbed Angerman, Lourie said.

Angerman was shot in a moment when Wersick was psychotic and suffering from "episodic discontrol," a condition in which a person's thinking "disorganizes under stress," Lourie testified.

Lourie acknowledged that an instant later Wersick could have recovered from the "episodic discontrol."

"When he saw the blood, that's when he snapped back out of it," Lourie stated.