A Montgomery County jury convicted a Potomac physician yesterday of second-degree murder in the bludgeoning death of his wife, rejecting both the prosecution's argument that he plotted the slaying and the defense's contention that the killing was committed by one of the couple's two grown sons.

After deliberating for about 38 hours over six days, jurors acquitted Zakaria M. Oweiss, 58, of first-degree premeditated murder, sparing him a possible life prison sentence in the death of Marianne Oweiss, 49, whose skull was crushed in the attack at the couple's home in August 2001. Second-degree murder is punishable by up to 30 years in prison.

Prosecutors said that Oweiss, in a fury over his wife's infidelity, pretended to go to work on the morning of Aug. 15, but then returned to their home on Kentsdale Drive and ambushed her, striking at least seven blows with a hard rubber mallet. But Oweiss's lawyer argued that the couple's son, Omar Oweiss, 22, who was home at the time, killed his mother during an argument because he was angry that her infidelity had ripped the family apart.

Omar Oweiss, who testified against his father, denied the allegation.

Zakaria Oweiss, who was admitted to a hospital with cardiac problems on Wednesday while the jury was deliberating, was not in the courtroom when the verdict was read yesterday afternoon. He watched the proceeding from Suburban Hospital via closed-circuit television.

"He was incredibly distressed at the verdict," his attorney, Peter Davis, said.

Though pleased that the jury had not returned a first-degree murder verdict, Oweiss suffered another "cardiac episode" as the impact of the second-degree murder conviction sank in, Davis said. He said Oweiss would appeal the verdict.

"We're not giving up on the defense," he said.

That defense -- which sought to fix blame on Omar Oweiss, a University of Maryland senior -- was sharply criticized by prosecutors, both in and out of the courtroom.

"I thought it was the vilest," said Deputy State's Attorney Katherine Winfree, who prosecuted the case. She said she was deeply moved by Omar Oweiss's "wrenching" predicament as the star witness against his father and the target of the defense's attack.

"It was just repugnant to me as a parent that a father could not only kill his wife, the mother of his two children, and then blame his own son," Winfree said. Fellow prosecutor Deborah Armstrong accused Davis of devising an "indecent" defense strategy. State's Attorney Douglas F. Gansler called the defense "morally depraved."

Davis brushed off the criticism. "I think you only have to look at the people making" the accusation, Davis said. "The defense was a genuine defense.''

He said the prosecution was guilty of misconduct for mishandling an important piece of evidence and for improperly protecting Omar Oweiss. Davis also said prosecutors had seriously damaged the integrity of their case by promising not to prosecute Omar Oweiss for perjury, despite his acknowledgment that he had lied to police and under oath on more than one occasion. Accompanied by a Montgomery County police detective as he left the courtroom yesterday, Omar Oweiss declined to comment.

The jury of eight men and four women, who were escorted from the courthouse by sheriff's deputies, declined to comment.

Montgomery County Circuit Judge S. Michael Pincus revoked Zakaria Oweiss's bond and scheduled sentencing for May 23. The defendant was to remain in Suburban Hospital under 24-hour guard while awaiting a heart procedure next week to treat a blocked artery, his lawyer said.

Acquitted of first-degree murder, Oweiss avoids a life sentence. His attorney said he plans to appeal the conviction.