Minutes after I discussed the tragic killing of Trayvon Martin on “The Last Word” last night, the Justice Department made a much-needed announcement. “The department will conduct a thorough and independent review of all of the evidence and take appropriate action at the conclusion of the investigation,” spokeswoman Xochitl Hinojosa said in a statement. The probe will include the Civil Rights Division of DOJ, the U.S. Attorney’s Office for the Middle District of Florida and the FBI.

This should bring a measure of relief to all of us who believe a man who guns down an unarmed child should not go unpunished. Yet, we must keep in check our expectations of the reach of federal civil rights law. The bar is high for federal prosecution. The state is another matter. That’s why news late this morning that the state attorney general has referred the Trayvon case to a grand jury is welcome news.

All of the information that has come out already paints a grisly portrait. An overzealous neighborhood watch captain in an SUV armed with a 9-mm handgun. A 17-year-old boy armed with an iced tea and a bag of Skittles. We know from Zimmerman’s 911 call that he thought Martin was “a real suspicious guy” who “looks like he’s up to no good or he’s on drugs or something.” And now we have some insight into Trayvon’s mindset at the time.

“He said this man was watching him, so he put his hoodie on. He said he lost the man,” said Trayvon’s girlfriend, who was talking with him on his cell phone during the start of the incident. In an exclusive ABC News report, she discussed the confrontation in answer to questions from the Martin family attorney.

“I asked Trayvon to run, and he said he was going to walk fast. I told him to run but he said he was not going to run.”

Eventually he would run, said the girl, thinking that he’d managed to escape. But suddenly the strange man was back, cornering Martin.

“Trayvon said, ‘What, are you following me for,’ and the man said, ‘What are you doing here.’ Next thing I hear is somebody pushing, and somebody pushed Trayvon because the head set just fell. I called him again and he didn’t answer the phone.”

That’s because Trayvon was dead of a single gunshot wound to his chest.

Zimmerman would claim self-defense. As ABC News reported, “The manual from the Neighborhood Watch program states: “It should be emphasized to members that they do not possess police powers. And they shall not carry weapons or pursue vehicles.” This, on top of ignoring, “We don’t need you to do that,” by Sanford police when he was asked if he were following Trayvon.

Florida’s insane “Stand Your Ground” law is a “get out of jail” card for the 28-year-old Zimmerman. According to the statute passed in 2005, “[A] person is justified in the use of deadly force and does not have a duty to retreat if: (1) He or she reasonably believes that such force is necessary to prevent imminent death or great bodily harm to himself or herself or another or to prevent the imminent commission of a forcible felony; . . .

From all that we know so far, Zimmerman was not justified in the use of deadly force. But his assertion of such was enough for Sanford Police Chief Bill Lee. “In this case, Mr. Zimmerman has made the statement of self-defense,” he said. “Until we can establish probable cause to dispute that, we don’t have the grounds to arrest him.” Perhaps that will change now that a grand jury is investigating.

There are a few notes of caution, however, for all those who are rightfully thrilled about DOJ’s involvement in the Trayvon case.  This has not been classified a hate crime. Only after its probe is complete can that determination be made. Next, notice these two key sentences in the DOJ statement.

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.  

But it is possible that prosecution for negligence, recklessness, mistakes and accidents could be done under Florida law. That’s why the parallel probe with the state is vital. My fervent hope is that if the feds ultimately can’t bring Zimmerman to justice, the state might. There’s a long way to go to holding Zimmerman accountable for his actions the night of Feb. 26. But at a minimum, his “get out of jail” card must be revoked.