Attorney General Eric Holder
Eric Holder is the first African American to hold the position of U.S. Attorney General. REUTERS

U.S. Attorney General Eric Holder Wednesday assured a prominent civil rights organization his Justice Department will conduct a thorough and independent review of the shooting of unarmed Florida teenager Trayvon Martin.

Holder spoke to the National Action Network, founded by the Rev. Al Sharpton, telling the audience the Justice Department will act on any evidence showing potential civil rights violations against Martin by George Zimmerman, a Sanford, Fla., neighborhood watch volunteer who fatally shot the 17-year-old during a Feb. 26 encounter in a gated community.

I know that many of you are greatly and rightly concerned about the recent shooting death of 17-year-old Trayvon Martin, a young man whose future has been lost to the ages, Holder said. If we find evidence of a potential federal criminal civil rights crime, we will take appropriate action and at every step the facts and the law will guide us forward.

The Justice Department opened a probe into the Martin case three weeks ago, preventing Holder from going into detail. The case sparked protests over the lack of any arrest in a shooting death of an unarmed black teenager by Zimmerman, 28.

Since the probe opened, Holder said the FBI officials and the Justice Department's peacemakers at the Community Relation Services have met with civil rights leaders, residents and law enforcement in Sanford, Fla., to alleviate tension over the shooting death.[VIDEO]

In addition, the department civil rights chief Assistant Attorney General Thomas Perez and U.S. Attorney Robert O'Neill of Florida have met with the Martin family and the community.

In all these discussions, we're listening carefully to concerns, Holder said. And we're emphasizing that the department will conduct a thorough and independent review of the evidence.

Meanwhile, Zimmerman, whom Florida authorities have described as a white Hispanic, has not been charged with any crime, maintaining he shot Martin in self-defense during a confrontation. Zimmerman obtained defense counsel, but they announced Tuesday they would no longer represent him for failing to return phone calls.

A special prosecutor in Florida recently said she would not bring the case to a grand jury, deciding to continue with her investigation.