Paul Wersick is overtaken at times by a "kind of terrible confusion," in which his thinking "gets messed up," part of reality "melts away," and he wants only to be cared for like a small child, a psychologist testified yesterday at Wersick's murder trial.

Clinical psychologist Charles Schwarzbeck III told the jury the he believes 16-year-old Wersick was suffering from this type of mental disorder - a "brief psychotic reaction" - when Montgomery County assessor George Angerman Jr. was killed last July in a Rockville parking garage.

Schwarzbeck was the third medical expert called by the defense to testify that Wersick was legally insane when Angerman was killed. The youth has pleaded innocent by reason of insanity to the murder charge against him.

Schwarzbeck, testifying as the trial in Montgomery County Circuit Court moved into its second week, said he had watched Wersick lapse into a state of "horrible confusion," in which "pieces of his thinking dissolved," during a battery of psychological tests he administered to Wersick earlier this month.

The psychologist stated that Wersick's mental state so alters what he sees at such times, "that it's not what other people see, the perceptions are distorted.

"When it happens . . . it's as though he were a little boy . . . saying 'Take care of me.'"

Wersick is accused of shooting Angerman once in the head after robbing him. The assessor's body was found in the front seat of his car, his mouth bound by a boy scout neckerchief, his left had tied with a piece of rope.

Under cross-examination, prosecutors asked Schwarzbeck what specific evidence he had of Wersick's "marked illogical thinking at the moment" Angerman was shot.

"I only have the evidence I saw in the test result," the psychologist answered.

Later, under questioning by the defense, Schwarzbeck said the nearly four hours of psychological tests administered to Wersick gave "pretty high-powered evidence . . . that this is a disturbed kid."