The Justice Department and the FBI, responding to a growing display of outrage, will open an investigation into the killing of Trayvon Martin, a 17 year-old African-American killed in a gated community in Sanford, Florida by a neighborhood watch captain.

The story of Martin’s death slowly but persistently reached the public consciousness in the three weeks since the incident on February 26. Martin, walking to a 7-Eleven near his father’s house for refreshments at halftime of the NBA All-Star game, was confronted by the watch captain (of a group that is not a registered neighborhood watch organization), George Zimmerman, who decided he was a suspicious character.

Zimmerman called in the perceived threat to a 911 dispatcher, a common occurrence for the criminal justice student and frequent reporter of disturbances to the police. Zimmerman then chased after Martin (against the wishes of the 911 dispatcher), confronted him, and fired a single shot that killed him. Zimmerman, who was licensed to carry a concealed weapon, was never arrested by police, and he claims to this day that he merely acted in self-defense. Florida has extremely lenient concealed weapons laws, and a “stand your ground” law that allows citizens to shoot a perceived threat without first retreating. This law has been used as the rationale for not prosecuting Zimmerman.

The story – and the 911 tapes, which have been made public – has engendered massive condemnation. Civil rights groups like Color of Change expressed outraged at the shooting of Martin, who was unarmed. The Sanford Police Department has been called to task for their resistance to prosecute Zimmerman (this is not the first time in recent years this department has failed to sanction crimes against African-Americans). Over 435,000 signed a petition on urging Zimmerman’s arrest. The Chairman of the Congressional Black Caucus, Emmanuel Cleaver, demanded an investigation into what he described as a “hate crime.” The Congressional Hispanic Caucus followed suit. Students throughout Florida rallied on behalf of Martin, with more rallies planned throughout the week.

Late yesterday, the Civil Rights Division of the Justice Department and FBI announced they would look into the killing. Here’s their statement:

The Justice Department’s Civil Rights Division, the U.S. Attorney’s Office for the Middle District of Florida, and the FBI opened an investigation into the facts and circumstances of the shooting death of Trayvon Martin. The department will conduct a thorough and independent review of all of the evidence and take appropriate action at the conclusion of the investigation. The department also is providing assistance to and cooperating with the state officials in their investigation into the incident. With all federal civil rights crimes, the government must prove beyond a reasonable doubt that a person acted intentionally and with the specific intent to do something which the law forbids – the highest level of intent in criminal law. Negligence, recklessness, mistakes and accidents are not prosecutable under the federal criminal civil rights laws. The Community Relations Service will be in Sanford, Fla., this week to meet with civil rights leaders, community leaders, and local law enforcement to address tension in the community.

It’s not clear from this document what the focus of the investigation would be, but it’s possible that they would look into a federal criminal sanction for Zimmerman as well as a probe into the conduct of the Sanford Police Department, given that a pattern has emerged over the years. Even Florida’s conservative state government plans to investigate the matter, which has taken on too much significance to ignore.