Around 3 a.m. on March 14 officers were responding to a car crash, and were told that one of the drivers had fled on foot.
Officer Mark Groff, checking the area for a suspect, testified during a prelminary hearing that he thought Nunez fit the description he had been given. When he got out of his cruiser to investigate, Nunez took off, Groff said, ignoring his shouts of "Stop; police!" Nunez jumped several fences before stumbling and falling in a darkened backyard.
As Groff caught up to him, Nunez scrambled to his feet. The officer testified that he saw Nunez reach for a metallic object in his waistband that he thought was a knife but turned out to be the pliers.
Groff said he hit Nunez with a heavy-duty flashlight three times, then pounced on him. The flashlight rolled away and Groff said he began using his fists. He said Nunez - though prone - continued to resist until backup arrived.
The beating caused a subdural hematoma, or bleeding on the brain. Nunez underwent an emergency craniotomy and stayed in the hospital for five days. A report by the attending physician said Nunez will need cognitive therapy.
At the hearing, Groff said he felt his life was endangered.
"I had no time to react. I thought I was about to be stabbed. I struck him with a flashlight," said Groff, 39, a 14-year police veteran.
Nunez has told his lawyer he doesn't remember anything after the first blow.
Chief William Heim cautioned against prejudging the evidence.
"It's very, very important for us to look as much as we can into the totality of the circumstances, and look at what a reasonable police officer would have done under similar circumstances," he said.
Nunez himself has been charged with aggravated assault, resisting arrest and escape after police said he fought with Groff and threatened him with a pair of pliers. A judge has ordered Nunez to stand trial.