The FBI began a parallel investigation into the February death of 17-year-old Trayvon Martin on Monday.

FBI agents were spotted in the gated community in Sanford, Fla., where the teen was shot dead by 28-year-old neighborhood watch captain George Zimmerman.

The agents are speaking with potential witnesses and investigating if the death of Martin was racially motivated, according to an FBI official who spoke to and confirmed the investigation to NBC News on Monday.

The state of Florida is conducting its own investigation with a special prosecutor looking into the case and two weeks ago the Justice Department's Civil Rights Division also announce that it would be looking into the possibility of civil rights violations.

Zimmerman's lawyer, Craig Sonner, has vehemently denied that the neighborhood watch captain's actions were motivated by race and maintains that his client acted in self-defense.

"George Zimmerman was acting in self-defense on the night in question, and when all the information is released, it will show that," Sonner told TIME Magazine.

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"The facts of the evening… have been spun by the media," he added.

This past weekend, two independent forensics experts told media outlets that screams for help recorded in a 911 call on the evening of Martin's death belonged to the late teen and not gunman George Zimmerman.

"That's a young man screaming," forensics expert Ed Primeau told the Orlando Sentinel. "I believe that's Trayvon Martin in the background, without a doubt."

The 17-year-old African-American was shot dead in a gated residential community on Feb. 26 by Zimmerman, who is part Hispanic. At the time of his death, Martin was unarmed wearing a hooded sweatshirt and carrying a bag of Skittles and a can of iced tea.

Zimmerman has yet to be arrested in the case, as police have cited Florida's "Stand Your Ground Law," which gives citizens leverage to use deadly force in the face of a threat. Nevertheless, national outcry, demonstrations, and debate has ensued across the U.S. and has led to the involvement of federal officials.