A Prince George's County Circuit Court jury was still deliberating well past 1 a.m. today in the trial of Steven Baines, who is charged with first-degree murder in the Feb. 2 shooting death of county police officer Antonio M. Kelsey. If convicted, Baines could be sentenced to death.

The deliberations, which began about 8:45 last night in the trial's seventh day, were interrupted briefly at about 12:15 a.m. by an incident that Judge Vincent J. Femia told the jury "comes under the definition of comic relief."

Femia explained that some members of the jury had apparently been mishandling an important item of evidence -- Kelsey's two-way hand radio -- in the jury room, and that portions of their discussions were being transmitted to county police headquarters and blocking regular radio traffic.

County police, who described the incident in more macabre tones, said that in addition to voice transmissions over the radio, they were getting an automatic "signal 13" -- police in trouble -- call from Kelsey's unit. After a brief period of alarm during which police tried to identify the source of the broadcast, they remembered that Kelsey's radio was in the custody of the court, and officers were dispatched to notify Judge Femia.

Femia agreed to a motion by Baines' attorney, R. Kenneth Mundy, to confiscate a recording of the transmission -- made routinely by police -- instructed jury members to refrain from handling the radio and sent them back to the jury room.

The shooting occurred when Kelsey, 22, working off duty in plain-clothes as a security guard at Cox's Liquors, 7600 George Palmer Hwy., Landover, chased Baines, 27, out of the store and down the street. The officer was later found lying on his back in a patch of grass, shot twice in the head with his own pistol.

Baines took the stand in his own defense Tuesday to testify that he shot Kelsey by accident while struggling for the officer's gun, thinking Kelsey was a robber.

But State's Attorney Arthur A. Marshall Jr. called the shooting "a purposeful and very deliberate act."

Baines "left a man there that he knew he had shot," Marshall told the jurors."You wouldn't do it to a dog."

Pacing back and forth in front of the jury box, Marshall began his closing statement by recounting the testimony of virtually every witness in the trial. Evidence proved Baines must have known Kelsey was a policeman, the prosecutor asserted.

Marshall pointed to a tape recording of Kelsey's radio transmissions to police headquarters while chasing Baines, saying it proved the officer was seeking to arrest the defendant for possession of marijuana that Baines had pulled out of his pocket in the store.

Baines must have seen -- or at least heard -- the walkie-talkie in Kelsey's hand while the officer chased and then wrestled with him, Marshall asserted.

In his turn, his voice often rising to a shout, Mundy attacked the prosecution's case. "If Steven Baines knew as he lay in that yard that Officer Kelsey was a police officer," the attorney asked, "do you think for one minute" that he would have deliberately killed him simply to avoid a drug arrest? "Do you think anybody would do it?"

"If [Kelsey] had said, 'I'm a police officer, here's my badge,' then we wouldn't be here," said Mundy.

The defense attorney attacked Marshall's recorded evidence. "If you listen to that tape, it's almost unintelligible," he said.

Mundy noted that Baines testified he only began struggling with Kelsey after the officer struck him on the head from behind and then put a gun to his head.

"Steven Baines believed he was in danger. Steven Baines ran to avoid a confrontation. He ran to avoid inflicting serious bodily harm on officer Kelsey.

"When Officer Kelsey struck Steven Baines on the back of the head, the law gave Steven Baines the right to protect himself, Mundy asserted.