But critics of the investigation into the death of 17-year-old Trayvon Martin at the hands of the Florida neighborhood watch volunteer have portrayed Zimmerman in other terms. They say he recklessly pursued Martin and possibly engaged in racial profiling.
They're demanding that Zimmerman, 28, be arrested in the death of Martin, who was shot last month while walking to the house of his father's fiancee after a trip to a Sanford convenience store.
Zimmerman has said he acted in self-defense.
The debate that has riveted the nation in the past few days has largely been framed in racial terms.
A police report describes Zimmerman as white; his family says he is Hispanic and he has wrongly been described as a racist. Martin was African-American.
On Wednesday, Martin's father, Tracy, said race played a role in the police investigation.
"Had Trayvon been a white kid ... Zimmerman would have been arrested," he said.
Critics have accused the Sanford Police Department of mishandling the case. Police Chief Bill Lee announced Thursday he is stepping down "temporarily" because he was becoming a distraction to the investigation.
The president of the NAACP, Benjamin Jealous, said Lee failed to do his job. "The reality is that this chief had probable cause to lock up a man who shot a boy in cold blood -- because he shot a boy in cold blood -- and he failed to do that," Jealous said.
Members of Martin's family were among demonstrators Wednesday in New York for a "Million Hoodie March," a reference to the attire the 17-year-old was wearing when he was shot.
"A black person in a hoodie isn't automatically suspicious," an online protest page said. "Let's put an end to racial profiling."
A former high school classmate painted a different picture of Zimmerman.
"A race thing? That is definitely not the case," Eric Gross of Greenville, South Carolina, said on Thursday. "He is by far not anywhere near a racist. I wasn't there, but he was a good guy."
The two attended Osbourn High School in Manassas, Virginia.
Zimmerman attended a four-month law-enforcement program in 2008 at the sheriff's office, said Kim Cannaday, spokeswoman for the Seminole County sheriff's office.
In his application for the course, Zimmerman wrote: "I hold law enforcement officers in the highest regard and I hope to one day become one."
Zimmerman has remained quiet over the shooting. His father said Zimmerman moved out of his home after receiving death threats. CNN has made numerous attempts to contact him, but has been unsuccessful.
The paths of Trayvon Martin and Zimmerman intersected on February 26.
The watch volunteer saw the youth and called 911 to report a suspicious man, authorities said.