A 23-year-old Mission man on trial for a second time in the death of a Lawrence man at a party in 2012 testified in his own defense Tuesday, saying he did the only thing he could have done at the time to protect a friend he believed to be in danger.

Justin P. Gonzalez is accused of hitting Nicholas Sardina over the head with a beer bottle and causing an injury that led to his death. He is charged with involuntary manslaughter.

Gonzalez, at times overcome with emotion, described the Feb. 24, 2012, party in the Oread neighborhood as a friendly affair where he caught up with old classmates from Bishop Miege High School and said goodbye to one who was headed off to basic training. It was friendly, Gonzalez said, until a group of people showed up about 2 a.m. with one of the residents of the home, who was angry the party hadn’t ended.

So, Gonzalez testified, he got his coat and prepared to leave. That’s when he saw one of his friends, Jake Anderson, arguing with an “older man” from the other group, he said in court Tuesday.

The argument got more and more heated until, Gonzalez testified, the “older man,” the 27-year-old Sardina, attacked the smaller Anderson, slamming him into a wall and punching him square in the face.

“Do you remember what it looked like?” asked Sarah Swain, Gonzalez’s attorney.

“Like he wanted to kill Jake,” Gonzalez said.

So, Gonzalez said, he hit Sardina in the head with the bottle of Dos Equis he was drinking, stopping the attack. Members of both groups started brawling. When the dust settled a few seconds later, Gonzalez said, he and Sardina shook hands.

Later that day, one of Gonzalez’s friends told him Sardina died hours after the fight.

Gonzalez’s retrial — the first trial took place last December resulted in a hung jury — continued Tuesday after beginning last week. The state rested its case after calling several more witnesses, including a forensic pathologist who testified that Sardina died as a result of a blood clot in the brain caused by blunt force trauma. At issue is whether Gonzalez, a college student and restaurant worker, acted in self-defense or used excessive force in striking Sardina, a former Kansas University student and Iraq War veteran.

“I thought (Anderson) could have been killed,” Gonzalez testified. “Nick didn’t look like he was going to stop at all. He was just locked in on Jake. I just did the only thing I could have done at that time to stop what Nick was doing.”

During cross-examination, the prosecution questioned Gonzalez on answers that didn’t match up with previous testimony, including how he knew Sardina, who he had never before met, was in the military; whether he suspected Sardina had weapons; and how he was holding the beer bottle before he struck Sardina.

“I’m trying to remember everything. It’s a lot,” Gonzalez said, admitting he was nervous.

His testimony picks back up when the trial continues Wednesday at 9 a.m.