Steven Baines, a Washington bricklayer who shot a Prince George's County police officer twice in the head on Feb. 2, was found guilty early yesterday morning of second-degree murder and illegal use of a handgun -- but acquitted of a first-degree murder charge that could have resulted in the death penalty.

The verdict came in at 6:35 a.m., when dozen weary jurors emerged after deliberating for almost 10 hours, into the morning of the trial's eighth day.

Baines, 27, was charged with the death of 22-year-old Antonio M. Kelsey, the first black county police officer slain in the line of duty. Baines faces a maximum prison term of 45 years.

The panel of six men and six women apparently rejected Baines' claim that he had shot Kelsey by accident while wrestling for the gun of the officer, who he said he mistook for a robber. The struggle took place after Kelsey chased Baines outside a Landover liquor store, where Kelsey was working off-duty as a plain-clothes security guard.

But the jurors also rejected the argument by State's Attorney Arthur A. Marshall Jr. that Baines had shot Kelsey with premeditation, in "a purposeful and very deliberate act."

"It's a fair verdict," Marshall said as he left the courtroom. "It was a clear compromise."

Defense counsel Joseph Gibson said the decision will be appeal.

The jury began its deliberations at 8:45 p.m. Wednesday, locked in a small room in the county courthouse in Upper Marlboro. Circuit Court Judge Vincent J. Femia, presiding in the case, vowed to keep the panel out until it reached a verdict.

The jury had heard impassioned arguments from Marshall and from chief defense attorney R. Kenneth Mundy, who claimed the prosecution had failed to prove beyond a reasonable doubt that Baines had willfully murdered Kelsey. The state's attorney said Kelsey had been trying to arrest Baines for possession of a bag of marijuana he displayed inside the liquor store.

Except for notes asking for candy, cigarettes and coffee, not a word was heard from the jurors for hours.

But shortly after midnight, county police went to Femia's chambers to tell the judge the jurors had been mishandling a key piece of evidence -- the slain officer's two-way hand radio -- and that portions of their deliberations possibly were being transmitted to police district headquarters in Seat Pleasant blocking regular radio traffic.

Femia pulled the jury back into the courtroom at 12:15 a.m. to tell them of the problem, which he said "comes under the definition of comic relief." County Police, however, described the incident in more macabre tones, saying dispatchers were receiving an automatic "signal 13" -- policemen in trouble call -- from Officer 910: Kelsey.

When dispatchers asked "Officer 910" to respond, police in the field recalled that the slain officer's radio was in the custody of the court, and Femia was notified.

The judge told the jurors not to mishandle the radio, and sent them into a second better-ventilated jury room. "It has cots, right?" asked one juror.

At 2:55 a.m., the jury sent the judge another note, asking for reinstruction on the legal penalties that could be considered against Baines.

The court reporter read back the judge's comments to the jury, and all parties resumed their wait for the verdict. Marshall paced back and forth in his fourth-floor office. Gibson sprawled across three plastic chairs in a futile effect to grab a few minutes of sleep. Femia opened his chambers and presided over a gathering of sheriff's deputies, police officers, court employes and anyone else who happened to wander in.

At 6:25 a.m., a phone range in Marshall's office. "Let's go," someone called. "We've got a verdict."

Baines looked straight ahead, expressionless, as the jurors rose together and their foreman announced the decision. Kelsey's brother Allegro stared into the defendant's back.

Femia dismissed the jurors, several of whom had tears in their eyes, and they filed out of the courtroom. Baines followed a moment later, hands cuffed behind his back as he was escorted back to jail.

Sentencing is scheduled Monday.