Thomas Junta took the stand in his own defense Wednesday and told jurors in his manslaughter trial that he was only trying to protect himself when he beat another hockey dad to death at a youth scrimmage.

The 44-year-old truck driver told a rapt Cambridge, Mass., courtroom that victim Michael Costin, with whom he had previously sparred over on-ice roughness, tried to sucker-punch him as he returned to an ice arena July 5, 2000.

"I didn't know what that guy was doing," Junta said, recalling his thoughts as Costin lunged at him and they fell together to the floor. "I mean, Why was he even jumping at me? It was so fast. It was like crazy."

During a fast-paced direct examination, Junta said Costin held one of his wrists while continuing to throw punches with the other and kick with both feet.

"Do you recall how many punches you threw at the man on that day?" defense lawyer Thomas Orlandi asked.

"No more than three," said Junta, adding that, after the third, Costin stopped punching and shielded his face. At that point, Junta said, "I kind of stopped and was almost sitting back onto the heels of my feet."

With his testimony, the defense rested. The jury in the case, considered the country's most extreme example of "sideline rage," is to hear closing arguments Thursday.

Junta testified in a quiet, flat voice, only becoming choked up as he recalled how upset his son and other children at the rink were after the fight. The father of two faces 20 years in prison if jurors do not accept his self-defense claim.

Prosecutors allege he attacked Costin, a father of four acting as an informal referee at the game, in a rage because Costin dismissed his concerns about body checking and other hitting among the players. Witnesses to the fight have given varied descriptions of the altercation, with some estimating Junta threw more than 10 punches and others saying only three.

Junta acknowledged that he became angry during "stick practice" at the Burbank Ice Arena in Reading. His 10-year-old son, Quinlan, and two friends were playing in a pick-up game against Costin's sons and their friends. When Junta told Costin he should better police the play, Costin replied, "That's hockey. That's how it's played," according to Junta.

Angry words outside the locker room soon turned into a wrestling match, Junta said. Costin, still in skates, shredded Junta's T-shirt during the fight and ripped a gold shamrock chain from his neck, testified Junta, who outweighed Costin by 100 pounds.

He said that, after rink employees separated them, he told his son to dress quickly and left the arena. Junta said that, after a minute in the parking lot, he began to worry about the safety of Quinlan and his friend who remained in the locker room.

"They were still inside the rink and we had just had this semi-brawl," he said.

Junta said he re-entered the building to get his son, ignoring a rink employee in the lobby. The woman, Nancy Blanchard, testified Monday that he was red-faced and pushed her violently out of the way when she tried to stop him.

Junta said that immediately as he passed through the main doors into the ice area, he saw Costin coming toward him.

"As I turned, he was already coming at me like this," said Junta, raising his right fist, "and I went like this with one arm," demonstrating a block, "and kind of ducked, and his knee started coming up too and he kind of like ended up on my back ... it was kind of like a tackle block."

After slamming into a nearby wall, Junta said, "we hit the floor and he pulled his knees up, trying to knee me and trying to get his feet around my shoulder area and then he started hitting me."

On cross-examination, prosecutor Sheila Calkins confronted Junta about why he hadn't backed down from the fight and left the arena.

"You didn't stand up and walk away?" she asked several times.

"He had my left wrist, ma'am. He wouldn't let go," Junta said.

"This is a 156-pound man, flat on his back, holding on to your wrist, and you want this jury to believe that you couldn't get away from him?" she continued.

"Yes, I do because that is the truth," Junta said.

Junta kept his composure as Calkins grilled him about what he described as "three off-balance punches" thrown in self-defense.

"You hit him the first time and you didn't stop to see if it was enough," said the prosecutor.

"No, because he didn't stop either," Junta said.

Calkins also showed him a picture of the bruise Blanchard said she got when he pushed her out of the way.

"How did Mrs. Blanchard get this bruise on her arm when you walked by her?" she asked.

"No idea. None," Junta said.

Before Junta took the stand, his son's friend Garrett, a 12-year-old hockey player (whose last name was withheld), gave his account of the fight. He said Costin jumped on Junta's back and continued trying to attack him until Junta delivered the last of three punches.

On cross-examination, however, he offered a time line of the fight that does not match other testimony, including Junta's. Garrett said he and Junta were in the parking lot waiting for Quinlan when Junta offered to buy him a soft drink. They walked together into the arena, Garrett said, and he had time to go to the vending machine and purchase a beverage while Junta waited in the doorway. It was only then, Garrett testified, that Costin assaulted Junta.

Also Wednesday morning, a defense medical expert testified that a single punch delivered with minimal force tore an artery in Costin's neck, killing him. Ira Kanfer, a pathologist with the Connecticut Medical Examiner's Office, contradicted a prosecution expert who told jurors Costin died from a punishing assault conducted with substantial force.

Pathologist Kanfer

Kanfer said the ruptured artery is "a rare injury caused by a minimum of force. It's just one of those things that happens."

"It's one blow that tears it. It's not multiple blows," he said.

But prosecutor Calkins pointed out that the doctor had not reviewed police reports or witness statements about the fight and ridiculed his assertion that Costin had only suffered "minimal trauma."

"Minimal trauma?" pressed Calkins. "You would consider that Mr. Junta, who is 270-plus pounds and 6-foot, on top of somebody punching them would be minimal force?"