Paul E. Wersick, 16, was found guilty yesterday of murdering a Montgomery County tax assessor who was attacked in a secluded underground garage, gagged with a Boy Scout neckerchief, robbed and shot once in the head last July.

The jury recommended the judge show mercy when he sentences the youth, who had pleaded innocent by reason of insanity.

Wersick sat expressionless as the jury pronounced him guilty of premediated murder and armed robbery. Minutes later, he was led out of the county courthouse in hand-cuffs, whisting "The Yellow Rose of Texas."

"Unfortunately, an awful lot of people feel he's a worthless dog who ought to be taken out and shot," Wersick's defense attorney, J. James McKenna, said after the verdict was rendered. "That's not so. He's a sick kid."

The defense brought in four psychiatric experts to testify that Wersick was a deeply disturbed teen-ager who killed assessor George Angerman Jr. while in a "psychotic state," unable to control his actions. But the jurors, faced with directly conflicting testimony from three prosecution psychiatric experts, used their own "common sense" to reach a verdict, according to two jurors.

A crucial factor in their decision was the belief that the crime had been "rather well-planned and carried out, though none of us felt it was the work of a master criminal," according to one juror.

A second important point was that "based on everything else we knew, he (Wersick) had not committed any irrational... bizarre acts in the past," this juror said.

The jurors said that because of conflicting testimony they discounted one psychiatrist's statement that Wersick, in a previous "psychotic state," had placed his pet cat in battery acid. A juror said a second psychiatrist had testified the incident involved "stepping on his cat's tail."

"We'd been presented with expert witnesses on both sides, and they don't agree. We didn't have the knowledge to judge which expert was right," this juror said. "So it came down to common sense." The jury spent more than 10 hours deliberating after closing arguments were completed Friday evening.

In their last poll before retiring at about 1 a.m. Saturday, at least four jurors voted to acquit Wersick on insanity grounds, according to several jurors. By that time, they all agreed he should be found guilty of using a handgun in commission of a felony, and were close to reaching agreement on a guilty verdict on the armed robbery charge, a juror said.

Yesterday morning when they returned to the courthouse, the jurors

Then, shortly before 1 p.m., a few minutes after they asked Montgomery County Circuit Court Judge Philip M. Fairbanks for a definition of a mercy recommendation, the jurors filed back into the courtroom and faced Wersick.

"Sane and guilty of felony murder in the first degree with mercy", the jury foreman read, and then delivered the guilty verdicts on the two other counts.

Felony murder, which carries a life sentence, involves commission of a murder while carrying out another felony, such as armed robbery. First degree murder involves premeditation. He will be sentenced June 8.

One juror said in an interview that the jury recommended mercy -- a recommendation that is in no way binding on the sentencing judge -- because of Wersick's age and "because he was to sick."

The defense, seeking an insanity finding, had contended that Wersick friends but always failing and living his life at the emotional level of a 3-year-old.

On July 10, upset over being "grounded" for misbehavior for an entire month. Wersick, "in a fit of infantile rage," set out "to make somebody else feel as bad as he did," according to testimony by defense witnesses. He took a bus to Rockville, and in an underground parking garage, found Angerman.

At some point while robbing the 36-year-old assessor, Wersick "had some change in his consciousness... he felt he could hear his own breathing, hear auto sounds, smell exhaust smells.... Then he heard a loud explosion, and at the moment after that he observed the man [Angerman] had blood on his face." That was the testimony of one of the defense's medical experts, all of whom said Wersick was "psychotic" and legally insane when the crime occurred.

Wersick, he told them, was "planning, plotting," when he left his Wheaton home on July 10, taking a gag, a rope and a concealed gun with him. "He locates a secluded place.... He stalks a vulnerable victim... subdues him... and takes only the items of value.

"After completing the robbery, he fires one shot... on well-placed, fatal shot. He is under control. He knows he is killing the only person who can identify him," the prosecutor said in his closing argument.

Earlier, psychiatrists called to the stand by the prosecution agreed with defense experts that Wersick is a disturbed youth, but they said he was never out of touch with reality nor legally insane at the time of the alleged shooting.

After yesterday's verdict, Nancy Allen, a Wheaton woman whose 11-year-old daughter was shot to death in a 1976 incident involving Wersick, watched Wersick leave the court-of Allen's daughter and placed him on probation.

Allen came almost every day to Wersick's trial in the Angerman case. Yesterday, speaking of the assessor's death, she said: "It never should have happened this time."

Angerman, who was 36 when he was killed, had been with the assessor's office for several years but was talking about striking out on his own soon in an assessing business, according to testimony at Wersick's trial. He had a 9-year-old daughter, whose custody he shared with his ex-wife, and he was engaged to be married.

Some of the slain assessor's relatives, who had sat through the 10-day trial, were in tears as they left the courthouse yesterday.

When asked about the mercy recommendation, Angerman's aunt, Laura Beller, said: I think it's good in a way. I'd rather they do that than come back another way, with an in