SANFORD, Fla. -- The white neighborhood watch volunteer in Florida whose fatal shooting of an unarmed black teen has sparked outrage appeared to be fixated on young black males, according to a report in The Miami Herald.

Criminal justice student George Zimmerman, 28, the self-appointed head of the neighborhood watch at the Retreat of Twin Lakes in Sanford, Fla., is credited with cracking some crimes and thwarting others, the Herald reports, but his shooting of 17-year-old Trayvon Martin is attracting criticism from across the country.

According to the Herald, Zimmerman would often go door-to-door in the neighborhood, warning residents to be careful of young black males. The news organization also reports Zimmerman was energetic in his efforts to protect the neighborhood, and that he contacted police 46 times since Jan. 1, 2011, to report disturbances, break-ins and other incidents.

"He would circle the block and circle it; it was weird," Teontae Amie, 17, told the Herald.

On the night of Martin's death on Feb. 26, Zimmerman telephoned police to report the presence of a "real suspicious guy" at the complex, the Herald reports. "This guy looks like he's up to no good," Zimmerman said. "These (expletive deleted) always get away."

Calls to 911 alerted police to cries for help that night, and to reports that the cries stopped after a shot was heard. Police learned Martin was walking to a convenience store for candy and iced tea, the Herald reports.

Zimmerman has told police that it was him crying for help; he claimed self-defense and has not been charged. The Herald says he was licensed to carry a firearm and admitted to the shooting.

Crime had been an issue at the complex, according to the Herald. There were eight burglaries, nine thefts and one other shooting in the year prior to Martin's death, it reports.

Martin's family attorney says Zimmerman was overzealous.

"Zimmerman felt he was one of them; he felt he was a cop," the lawyer, Natalie Jackson, tells the Herald.