CAMBRIDGE, Mass. - The jury in the manslaughter case against a hockey dad began deliberating yesterday whether he was a "gentle giant" who fought back in self-defense, or just a bully.

Thomas Junta, 44, could get up to 20 years in prison if convicted of beating another father to death in a case that has drawn national attention to parental violence at youth sporting events.

Junta claimed he was defending himself when he beat Michael Costin, 40, into unconsciousness on July 5, 2000, in an argument over rough play at their sons' hockey practice. Several young skaters, including the men's sons, witnessed the fight between the 270-pound Junta and Costin, who was an inch shorter and 114 pounds smaller.

"Send Tom Junta back to his hockey family," defense attorney Thomas Orlandi Jr. urged the jury during closing arguments. He described his client as a "gentle giant" worried over what the other man might do.

Prosecutors mocked that description, saying Junta used his size to overpower Costin and pummeled him in an attack that ruptured an artery in Costin's neck.

Prosecutor Sheila Calkins dropped to her knees before the jury and flailed her arms as she described how the burly truck driver struck the other man as he lay on the ground beneath him. She said Junta left Costin to die.

"He took (Costin's) head, and he slammed it into the mat," she said. "The 'gentle giant.'"

Junta listened to closing arguments with one elbow on the defense table, his head resting on his fist, his eyes cast downward.

Costin's four children - three boys who were at the rink the day of the fight and a younger daughter - were in the courtroom as the trial wrapped up. Junta's 17-year-old daughter and 12-year-old son, Quinlan, who testified in his father's defense, were also there.

Jurors deliberated about 31/2 hours yesterday before recessing for the night. They were to resume today.

The judge said the jury may consider manslaughter as well as involuntary manslaughter. Both charges carry up to 20 years in prison, but guidelines for first-time offenders like Junta call for much shorter sentences.

The dispute between the two men started when Junta grew angry at rough play during what was supposed to be a non-contact scrimmage. Costin, who was supervising the game, told him: "That's hockey" and they exchanged profanities. After the game, the two men scuffled before they were pulled apart.

Junta claimed Costin ripped his shirt, tore a chain from around his neck and scratched his arms. Photographs showed injuries that included a cut above a Snoopy tattoo on one of his arms.

Junta left the rink but returned a few minutes later. He said Costin took a swing at him as he walked in.

"This little 160-pound guy was ready to take him out," Orlandi said. "Fortunately Mr. Junta spotted him at the last minute and ducked."

The men then fell to the ground. Junta said he punched Costin three quick times as Costin, who was on his back, tried to punch and kick him.

"He defended himself against that force, as he had a right to do," Orlandi said. "Once that force was neutralized, he was out of harm's way, he stopped. He returned to his kids. He walked away from Costin."

Orlandi also reminded jurors that a 21-year-old college hockey player recalled seeing Junta land only three punches.

But prosecution witnesses said Junta stormed back into the rink after the first fight, aside Nancy Blanchard, a rink employee, who tried to tell him to leave. She and another woman both testified Junta landed repeated blows as they yelled: "Stop! You're going to kill him."

Earlier this week, Quinlan Junta testified under the gaze of his father, supporting the defense argument that the fatal brawl ended after just a few blows. A day later, his dad took the stand.

Shedding tears at times during his testimony Wednesday, Junta said he left the rink without knowing how gravely he had injured Costin. He said the other man had acted "crazy."

"I just wanted him to stop hitting me," he testified.