George Zimmerman has said repeatedly that he was fighting for his life the night he killed Trayvon Martin, an unarmed 17-year-old who was found with a can of iced tea and a bag of Skittles. He was punched in the nose. His head was slammed repeatedly into the sidewalk. His mouth and nose were covered by Martin. But when Zimmerman sat for his final interview with Sanford Police detectives Christopher Serino and Doris Singleton, he was confronted with a pesky perception. His injuries didn’t match the severity of the story he told.

“As far as 25 and 30 punches,” Serino said at the Feb. 29 sit-down, “I’ve consulted with a lot of people, not quite consistent with your injuries. You do have injuries, however.” Yes, Zimmerman did have injuries — a broken nose and cuts on the back of his head. “I was on my back . . . he kept punching me,” Zimmerman explained. “And then when I started yelling for help that’s when he grabbed my head started to slam it.” Zimmerman told the detective he couldn’t remember how his head was slammed into the sidewalk or how many times he was punched in the nose. He also told Serino that he had no bruises or fractured ribs or other injuries.

Zimmerman’s cuts and lacerations were “not really coinciding with being slammed hard into the ground,” Serino said. “Skull fractures usually happen with that. I’ve seen them all.” Later in the interview, the detective apparently showed Zimmerman a piece of paper or a photograph and noted, “Once again, these are your defensive wounds, which are essentially nonexistent. I’m looking for bruising and scrapings and I don’t see. . . . You fared pretty well, probably because you had long sleeves on. . .

What Serino also couldn’t understand was what could have set Martin off to attack Zimmerman in the manner he said he was. “The question is what enraged him so badly,” he asked.

Pointing out that Zimmerman had two opportunities to identify himself to Martin as a person who didn’t mean to do him harm, Serino said, “The problem being in his mind is, which I can’t get into because he’s passed, he perceived you as a threat. . . . He has every right to defend himself, especially when you are reaching into your pocket to grab the cellphone.

“What do you think his motivation was? The kid had no violent background. No violent tendencies that we can find,” Serino said. “What made him snap? He’s not on drugs. Can you fill in that blank? . . . What do you think set him off?” Serino asked.

“I don’t know,” Zimmerman replied.

“Had he been a goon, a bad kid, two thumbs up,” Serino continued. “No. He does not fit the profile of what occurred, which is another unfortunate thing we got going on here.”

Serino concludes this line of inquiry with an instantly memorable line. “I want to know, everybody wants to know, what set him off. He’s not on PCP. He’s not on anything. He’s on Skittles.”