WASHINGTON -- Attorney General Eric Holder vowed Monday to continue a federal investigation into the shooting death in Florida of Trayvon Martin, but other officials said the government may not be able to charge George Zimmerman with a federal hate crime because it's not clear that he killed the 17-year-old youth because of his race.
The weakness of the evidence compounds political problems facing President Barack Obama and Mr. Holder, who are under mounting pressure from many liberal and African-American groups to bring a federal case against Mr. Zimmerman after a Florida jury acquitted him Saturday of second-degree murder and manslaughter.
Mr. Obama has responded cautiously to the national uproar, making no public comments beyond a carefully worded statement Sunday.
Instead, Mr. Holder is acting as the administration's spokesman on the matter, saying in a speech Monday that the Martin killing was a "tragic, unnecessary shooting death." At a previously scheduled luncheon celebrating the Delta Sigma Theta sorority, a large audience of black women broke into applause when the attorney general said, "I share your concern."
"We are determined to meet division and confusion with understanding and compassion -- and also with truth," Mr. Holder said, adding: "We will never stop working to ensure that -- in every case, in every circumstance and in every community -- justice must be done."
Justice Department lawyers are reviewing an investigation of the Martin shooting begun last year in conjunction with the FBI and Florida state prosecutors, officials said. Prosecutors are combing through that evidence, as well as testimony from Mr. Zimmerman's state trial, to determine whether to file civil rights charges.
Privately, several Justice Department officials agreed such charges would be problematic for several reasons, including the difficulty in proving motive and the challenge posed by Mr. Zimmerman's state court acquittal.
The Florida jury acquitted Mr. Zimmerman after his attorneys used a self-defense argument.
Mr. Zimmerman, 29, a neighborhood watchman, saw the hoodie-clad teen walking through his gated community on a rainy night in February 2012 and followed him. He said he fired his pistol after the teenager punched him, knocked him down and started pounding his head into a concrete walkway. Prosecutors said Mr. Zimmerman racially profiled the youth and initiated the confrontation that resulted in the death.
The verdict brought protests from civil rights organizations and demands for federal action.
The NAACP started a petition late Saturday to urge the department to file civil rights charges against Mr. Zimmerman. The petition received such a massive response that it crashed the organization's website.
Mr. Obama, the nation's first African-American president, has often struggled to find his footing in confronting sensitive issues of race. And Mr. Holder, the nation's first black attorney general, increasingly has become Mr. Obama's voice on controversial racial issues.
Mr. Holder is a liaison to black advocacy groups and pushes an aggressive civil rights agenda, at times providing the White House cover when Mr. Obama chooses not to get involved. Today, Mr. Holder will address the NAACP's annual convention in Orlando, Fla., not far from Sanford, where the trial was held.
White House press secretary Jay Carney said Monday that Mr. Obama "has no opinion to express" about the Justice Department investigation, or whether federal charges should be brought against Zimmerman.