This Feb. 27 photo released by the State Attorney's Office on May 17 shows George Zimmerman, the neighborhood watch volunteer who shot Trayvon Martin, with blood on the back of his head.

Photo released today shows George Zimmerman, the neighborhood watch volunteer, on the day he shot Trayvon Martin.

The Kel-Tec PF-9 9mm handgun used by George Zimmerman, the neighborhood watch volunteer, to shoot Trayvon Martin is shown in a newly released photo.

George Zimmerman, left, walks out of the intake building at the John E. Polk Correctional Facility with an unidentified man, April 22, in Sanford, Fla. Zimmerman posted bail on a $150,000 bond on a second degree murder charge in the February shooting death of 17-year-old Trayvon Martin in Sanford, Fla.

George Zimmerman George Zimmerman walks back to his seat after taking the stand during his bond hearing in a Seminole County courtroom on April 20 in Sanford, Fla.

Mark O'Mara, attorney for George Zimmerman, addresses the media following a bail hearing for Zimmerman.

Sybrina Fulton and Tracy Martin, the parents of slain Florida teenager Trayvon Martin, are escorted into the Seminole County Criminal Justice Center by their attorney Benjamin Crump for a bond hearing for George Zimmerman, in Sanford, Fla.

The parents of Trayvon Martin, Tracy Martin (2nd-L) and Sybrina Fulton (3rd-R) hold hands as they watch a news conference on April 11 in Washington D.C. as special prosecutor Angela Corey in Sanford, Florida, announces charges against George Zimmerman.

State Attorney Angela Corey, special prosecutor in the Trayvon Martin case, center, announces during a news conference in Jacksonville, Fla. on April 11 that George Zimmerman will be charged with second-degree murder in the shooting death of Trayvon Martin.

Deloyd Parker, right, tells Lee Rhyne about Trayvon Martin as they watch State Attorney Angela Corey, special prosecutor in the case, announce during a news conference that George Zimmerman will be charged with second-degree murder in the shooting death of Martin, The two watched the news conference at the SHAPE community center in Houston on April 11.

Dorothy Jackson (center) and others pray together for Trayvon Martin at the Allen Chapel A.M.E. church in Sanford, Fla. on April 11 after the Florida Special Prosecutor, Angela Corey, announced to the media that George Zimmerman has been charged with second degree murder in the death of Martin.

A man, who identified himself as Mohawk Gaz, sports an image of Trayvon Martin on his hair during a rally to protest his killing in Miami, Florida April 1, 2012. Thousands of protesters gathered in a downtown bayfront park on Sunday demanding the arrest of the neighborhood watch volunteer who shot and killed the unarmed black teenager, Trayvon Martin, in central Florida a month ago.

Mohawk Gaz wears a picture of Trayvon Martin in his hair along with his name as he and other supporters gather for a rally in his honor at the Bayfront Amphitheater on April 1, 2012 in Miami, Florida.

Demonstrators hold signs aloft as they march during an NAACP march and rally to the Sanford Police Department for Trayvon Martin in Sanford, Fla., March 31. Sanford is the town where Trayvon Martin, 17, was shot dead on Feb. 26 after George Zimmerman, 28, a Hispanic neighborhood watch captain, believed the young man walking through the gated community in a hooded sweatshirt looked suspicious.

Trayvon Martin supporters march through the historically African American community of Goldsboro on their way to an NAACP rally in front of the Sanford Police Department on March 31, in Sanford, Fla.

Demonstrators march during an NAACP march and rally for Trayvon Martin in Sanford, Fla., March 31.

Members of the National Black United Front hold a Trayvon Martin Solidarity Rally outside the U.S. Department of Justice on March 26, 2012 in Washington, DC. Trayvon Martin, a 17-year-old Florida high school student, was shot and killed, in Sanford, Florida on Feb. 26.

Trayvon Martin supporters hold hands while marching through downtown, March 26, 2012, before the start of a town hall meeting about Martin's death in Sanford, Florida. The teenager's family addressed the town hall meeting along with Rev. Al Sharpton. Martin was killed by George Michael Zimmerman while on neighborhood watch patrol in the city.

Patrick Mulchay, center, joins other congregants in song during a service at Middle Collegiate Church in New York on March 25.

A man wears a hoodie before the start of a service at Middle Collegiate Church in New York.

Congregants arrive at Middle Collegiate Church in New York on March 25.

People gather at a "Stand Up for Trayvon Martin" rally in Washington March 24. Many participants gathered in all black attire or hoodie sweatshirts, or carried tea and Skittles, in memory of the 17-year-old high school student who was shot and killed last month by a neighborhood watch captain in Sanford, Fla,

Supporters hold hands during a prayer vigil for Trayvon Martin at Allen Chapel AME church on March 23, in Sanford, Fla.

Michael M. Krop Senior High School students carry signs and chant during a rally demanding justice for Trayvon Martin, Friday, March 23, in Miami Gardens, Fla.