ELLICOTT CITY, MD., FEB. 22 -- A Circuit Court jury found a 23-year-old Howard County man guilty today of instigating a brawl that resulted in the severe beatings of two brothers at a Columbia movie theater.

It took the jury less than 30 minutes to convict Terrence Kelly, a crew foreman at a Washington sprinkler manufacturing company, on two counts each of assault and battery and one count of disturbing the peace, common law crimes that do not carry automatic prison terms.

Kelly, who made the unusual decision to represent himself during his two-day trial, had been accused of engaging William and Robert Murphy in a fight at a screening of "The Untouchables" at the Columbia Cinema last June.

Both sides testified that the fight began after William Murphy asked Kelly to be quiet. The altercation eventually grew to include a group of five to seven other men and ended after the brothers had been kicked and beaten unconscious.

Assistant State's Attorney Richard O'Connor said he would ask Judge Robert F. Fischer to impose a 20-year prison term when Kelly, who is free on a $5,000 bond, returns to court for sentencing on May 3.

"He's been a thorn in the side of the citizens long enough," O'Connor said, adding that Kelly had been convicted of burglary and was on probation for a battery conviction at the time of the June theater brawl.

Although Kelly maintained that he had acted in self-defense because William Murphy had pushed him first, he said he was not surprised by the verdicts.

He acknowledged that some of his statements -- in particular that he had resumed watching the movie while the Murphys were getting beaten by others and would do the same thing again -- probably hadn't sat well with the jurors. He said he plans to bring a lawyer the next time he comes to court.

On the witness stand yesterday, both brothers gave a harrowing account of how a summer night's visit to a neighborhood movie theater ended with their suffering concussions, bruises and other injuries.

William Murphy, 25, said that after he had asked Kelly a third time to lower his voice, Kelly stood and challenged him to a fight. The pair exchanged a few heated words and then took their seats again, but a few minutes later Kelly moved down the aisle and positioned his body in front of Murphy, who then tried to push him away, he said.

Both Kelly and William Murphy testified that Kelly responded to the shove by grabbing Murphy by the neck. At that point, Robert Murphy, 27, tried to intervene on his brother's behalf, and he testified that Kelly then punched him, an allegation that Kelly denied. The brothers said they were unclear about how the other men got involved, but recalled getting dragged toward the front of the theater by the group and being beaten some more while no one in the audience came forward to help.

No other arrests have been made in the case.

Outside the courtroom, Robert Murphy said he hadn't been to a public theater since June and that he instead watches movies on the videocassette recorder his father gave him after the ordeal.

The Murphys are the sons of Prince George's County School Superintendent John A. Murphy.