Win Mcnamee/Getty Images State Attorney Angela Corey, right, held a news conference on charges to be brought against George Zimmerman in the Trayvon Martin shooting, in Jacksonville, Fla. JACKSONVILLE, Fla. - The Florida special prosecutor announced a second-degree murder charge on Wednesday against George Zimmerman in the shooting death of Trayvon Martin. What the Charge Means By choosing to charge George Zimmerman with second-degree murder in the killing of Trayvon Martin, Florida Special Prosecutor Angela B. Corey selected the toughest possible charge involving a killing, short of first-degree murder, which requires a finding of premeditation and carries the death penalty as a possible punishment. Under second-degree murder, the jury must find that a death was caused by a criminal act "demonstrating a depraved mind without regard for human life," said Eric Abrahamsen, a Tallahassee criminal defense lawyer, reading from the state's standard jury instructions. The jury would be able to reject the murder charge, however, and opt for a lesser offense, including charges like manslaughter. The maximum sentence for second-degree murder is life in prison. Angela B. Corey, the prosecutor, said Mr. Zimmerman, 28, a crime watch volunteer, was in the custody of law enforcement officers in Florida. He is accused of fatally shooting Mr. Martin, an unarmed teenager, in a case that has captivated the country and brought to the fore issues of race, violence and precisely what constitutes self-defense. "We did not come to this decision lightly," Ms. Corey said. She added, "Let me emphasize that we do not prosecute by public pressure or by petition." "We will continue to seek the truth about this case," she said. Ms. Corey opened the news conference by saying that she had spoken to Trayvon Martin's parents shortly after she took on the case, and that the investigation was driven by "the search for justice for Trayvon." "It was less than three weeks ago that we told those sweet parents that we would get answers," she said. Critical to the case is the question of whether or not the shooting fell under Florida's "Stand Your Ground" law, which gives wide leeway to people who claim self-defense, and which does not require people to retreat before using deadly force. Ms. Corey said that her office regularly deals with Stand Your Ground motions. "If Stand Your Ground becomes an issue, we will fight it," she said. He has not spoken publicly since the shooting . Mark O'Mara, a criminal defense lawyer from Orlando, announced that he is now representing Mr. Zimmerman. At a news conference in Washington, D.C., Trayvon's parents, Sybrina Fulton and Tracy Martin, said the charges had started the healing process, but Mr. Martin said, "We will continue to walk until the right thing is done." Ms. Fulton thanked the family's supporters, saying "a heart has no color. It's not black. It's not white. It's red, and I want to say thank you from my heart to your heart. Benjamin Crump, a lawyer representing the family, said that Ms. Corey prayed with Trayvon's parents but "did not make one promise to the family that she would prosecute," only that she would look hard at the evidence. Mr. Crump also thanked the people behind an online petition that helped begin the online conversation about the case and "the young people who believed completely in justice; the idea, the concept, the dream of justice." On Tuesday, Mr. Zimmerman's previous lawyers, Craig Sonner and Hal Uhrig, announced that they were withdrawing from his legal team. Serge F. Kovaleski contributed reporting from Sanford, Michael S. Schmidt from Washington and Timothy Williams from New York.