But doesn't the double jeopardy bar a federal prosecution after a complete acquittal in state court?
Nope. Although the Fifth Amendment provides, "nor shall any person be subject for the same offence to be twice put in jeopardy of life or limb," the Supreme Court in Abbate v. United States, 359 U.S. 187 (1959), said the dual sovereignty doctrine permits both the State and the Feds to prosecute the same person for the same crime:
The basic dilemma was recognized over a century ago in Fox v. Ohio. As was there pointed out, if the States are free to prosecute criminal acts violating their laws, and the resultant state prosecutions bar federal prosecutions based on the same acts, federal law enforcement must necessarily be hindered. For example, the petitioners in this case insist that their Illinois convictions resulting in three months' prison sentences should bar this federal prosecution which could result in a sentence of up to five years. Such a disparity will very often arise when, as in this case, the defendants' acts impinge more seriously on a federal interest than on a state interest. But no one would suggest that, in order to maintain the effectiveness of federal law enforcement, it is desirable completely to displace state power to prosecute crimes based on acts which might also violate federal law. This would bring about a marked change in the distribution of powers to administer criminal justice, for the States under our federal system have the principal responsibility for defining and prosecuting crimes. See Screws v. United States, 325 U. S. 91, 109; Jerome v. United States, 318 U. S. 101, 104-105. Thus, unless the federal authorities could somehow insure that there would be no state prosecutions for particular acts that also constitute federal offenses, the efficiency of federal law enforcement must suffer if the Double Jeopardy Clause prevents successive state and federal prosecutions. Needless to say, it would be highly impractical for the federal authorities to attempt to keep informed of all state prosecutions which might bear on federal offenses.
Even though the law allows for a federal prosecution, it seems extremely unlikely in this case for all sorts of policy reasons.
The DOJ issued this statement, saying its investigation was ongoing:
JUSTICE DEPARTMENT STATEMENT ON THE TRAYVON MARTIN-GEORGE ZIMMERMAN CASE
As the Department first acknowledged last year, we have an open investigation into the death of Trayvon Martin. The Department of Justice's Criminal Section of the Civil Rights Division, the United States Attorney's Office for the Middle District of Florida, and the Federal Bureau of Investigation continue to evaluate the evidence generated during the federal investigation, as well as the evidence and testimony from the state trial. Experienced federal prosecutors will determine whether the evidence reveals a prosecutable violation of any of the limited federal criminal civil rights statutes within our jurisdiction, and whether federal prosecution is appropriate in accordance with the Department's policy governing successive federal prosecution following a state trial.
The Herald quotes friends of the blog here:
Jurors found that prosecutors failed to prove the more serious second-degree charge that Zimmerman, the neighborhood watchman at a Sanford gated community, possessed “ill-will,” “hatred” or “spite” in the fatal shooting of Martin. Instead, the six female jurors found that Zimmerman acted in self-defense.
Consequently, experts said, it would be legally inconsistent for the Justice Department to consider filing criminal charges against Zimmerman under the federal Shepard-Byrd Hate Crimes Prevention Act of 2009. Generally, that law prohibits someone from “willfully causing bodily injury” to another person because of his race, color, religion or national origin.
“If the state jury had been persuaded beyond a reasonable doubt that Zimmerman caused bodily harm to Trayvon Martin because of Martin’s race, it would have almost certainly convicted Zimmerman of second-degree murder, which requires proof of ‘ill-will’ or ‘malice,’” said Scott Srebnick, a prominent federal criminal defense attorney in Miami. “So, to bring a federal civil-rights prosecution against Zimmerman, the attorney general would essentially be second-guessing the state jury’s verdict as opposed to vindicating a different or broader federal interest.”
Srebnick added: “I find it doubtful that the attorney general will pursue a prosecution on a civil rights theory simply out of displeasure with the state jury’s verdict.”
Brian Tannebaum, a Miami defense attorney and past president of the Florida Association of Criminal Defense Lawyers, agreed.
“People are comparing this case to Rodney King, where there was a federal prosecution after a state acquittal, but the difference there was there were witnesses, specifically the video everyone still remembers,” Tannebaum said, referring to a man’s sensational videotape of the police beating.