(CNN) -- George Zimmerman, charged with second-degree murder in the shooting death of Trayvon Martin, had a "little hero complex" but was not a racist, a Sanford, Florida, homicide investigator told federal agents, according to reports released Thursday.
In an interview with FBI agents in March, investigator Chris Serino told authorities he "believed that Zimmerman's actions were not based on Martin's skin color, rather based on his attire, the total circumstances of the encounter and the previous burglary suspects in the community," according to an FBI report.
The reports and other information in the second-degree murder case against Zimmerman were released Thursday by Special Prosecutor Angela Corey to Zimmerman's attorney.
The U.S. Department of Justice took up a civil rights investigation following allegations that race played a part in the killing of Martin, 17, in February in a gated community in Sanford, Florida. The reports released Thursday do not draw conclusions in that investigation.
Martin's family and supporters say Zimmerman racially profiled the teen, describing him as "suspicious" during a 911 call and ignoring a police dispatcher's request that he not follow him.
The 28-year-old neighborhood watch volunteer has said he killed Martin in self-defense, saying the teen punched him and slammed his head into a sidewalk before the shooting, according to family members and police.
Among the evidence released Thursday are details about federal interviews with more than 30 people, including key members of the Sanford Police Department and Zimmerman's neighbors and co-workers.
In his interview, Serino explained to the FBI agents that African-American gangs in the community "typically dressed in black and wore hoodies," the report said.
"Serino believes that when Zimmerman saw Martin in a hoody (sic), Zimmerman took it upon himself to view Martin as acting suspicious," the report said. "Serino described Zimmerman as overzealous and as having 'a little hero complex,' but not as a racist. Serino explained that on numerous occasions he asked Zimmerman specifically if he followed Martin based on his skin color and Zimmerman never admitted to this fact."
In June, Sanford police said Serino had "voluntarily" asked to be moved from detective to patrol officer. At the time, police Sgt. David Morgenstern said that the move was not a demotion and that he did not know why Serino made the request.
Many of Zimmerman's neighbors, whose identities are redacted, told federal agents they did not know him. And those who did have nothing derogatory to say about him.
Similarly, interviewed co-workers are complimentary of Zimmerman. Several noted an incident in which a lock Zimmerman used to attach his orthopedic chair to his desk was cut, but said he handled it appropriately and professionally.
One apparent co-worker, whose identity was redacted, told agents she saw Zimmerman as he was waiting to speak to human resources the Monday after the shooting and noticed his injuries. The woman told agents that Zimmerman was "absolutely emotionally devastated."
Another FBI report documents a March 30 interview with a store owner who contacted authorities to say Zimmerman had contacted him about two weeks earlier "in reference to purchasing a new firearm." Zimmerman told the owner, whose identity was redacted, that "his life is in danger and he needs more guns," the report said. It was unclear from the report whether Zimmerman purchased the firearm.
The evidence also included audio of conversations between 911 dispatchers and Sanford police.
The dispatcher tells officers to look for a "black male, late teens, wearing a dark gray hoodie and sweatpants, walking around," adding that the youth was last seen running toward the back of the neighborhood.
Then, says the dispatcher, "There's screaming and a gunshot, are you responding?" Dispatchers later tell responding officers they have received a total of four calls regarding the incident. "Someone's laying in the backyard," a dispatcher says.
"I need somebody ASAP," an officer says on the recording. "I've got one down with a gunshot wound, and I've got one secure."
Also released were reports on interviews with agents of the Florida Division of Alcoholic Beverages and Tobacco, who arrested Zimmerman in 2005 on suspicion of battery against a law enforcement officer and obstruction of justice. The agents told authorities that Zimmerman did not use racial slurs or discriminatory language during the incident, the reports said.
The charges against Zimmerman, who was accused of pushing an undercover agent, were later dropped after he entered a pretrial diversion program and completed an anger management class.
A report on an interview with Zimmerman's ex-fiance was also released. The woman told authorities that while she and Zimmerman had physical altercations and at one point filed restraining orders against one another, she never saw Zimmerman exhibit any other violence or exhibit any racial bias.
Additionally, details about Zimmerman's MySpace account, surveillance video and e-mails between Zimmerman and ousted Sanford Police Chief Bill Lee were released as part of the evidence handover.
On the MySpace account in the name of "Joe G.," Zimmerman, a white Hispanic, recalls moving from Manassas, Virginia, saying, "I don't miss driving around scared to hit Mexicans walkin on the side of the street, soft ass wanna be thugs messin with peoples cars when they ain't around (what are you provin, that you can dent a car when no ones watchin) don't make you a man in my book. Working 96 hours to get a decent pay check, getting knifes pulled on you by every Mexican you run into."
Also released were copies of the e-mails between Zimmerman and Lee before the shooting regarding the neighborhood watch program. Zimmerman, in the e-mails, notes there has been a "spike in robberies and home invasions in the neighborhood within the past two months."
He adds that he has not had a positive view of Sanford police because of the "Sherman Ware incident." Ware, a black homeless man, was beaten by a Sanford police lieutenant's son. Zimmerman was critical of police handling of the case and reportedly worked on Ware's behalf.
Zimmerman was released on $1 million bond last week. An initial bond of $150,000 was revoked last month after a judge learned that Zimmerman and his wife failed to disclose more than $150,000 in donations from the public.