George Zimmerman's self-defense claim could be hurt by his own witnesses, who have changed their accounts since they were interviewed early on in the Trayvon Martin case.

The Orlando Sentinel reported that four witnesses' statements regarding the Feb. 26 shooting changed significantly when they were interviewed a second time in March. The statements are included in the collection of evidence officially released by the State Attorney's Office last week.

Here is an overview of the key changes in their accounts, as reported by the Sentinel.

Witness 2

A young woman who lives in the Retreat at Twin Lakes community, where Trayvon was shot, was interviewed twice by Sanford police and once by the Florida Department of Law Enforcement.

She told authorities that she had taken out her contact lenses just before the incident. In her first recorded interview with Sanford police four days after the shooting, she told lead Investigator Chris Serino, "I saw two guys running. Couldn't tell you who was in front, who was behind."

She stepped away from her window, and when she looked again, she "saw a fistfight. Just fists. I don't know who was hitting who."

A week later, she added a detail when talking again to Serino: During the chase, the two figures had been 10 feet apart.

That all changed when she was reinterviewed March 20 by an FDLE agent. That time, she recalled catching a glimpse of just one running figure, she told FDLE Investigator John Batchelor, and she heard the person more than saw him.

"I couldn't tell you if it was a man, a woman, a kid, black or white. I couldn't tell you because it was dark and because I didn't have my contacts on or glasses. … I just know I saw a person out there."

Witness 12 was interviewed on March 20, saying she "didn't know which one" was on top of the other during the scuffle. Six days later, she said she was sure it was Zimmerman on top, the Sentinel reported.

Witness 6 lived close to where the incident occurred. On the night of the shooting, he told investigators that Martin was on top, "just throwing down blows on the guy, MMA-style," the paper reported. He also noted that Zimmerman was calling for help. But three weeks later, the witness said he wasn't sure who was calling for help.

Witness 13 said he spotted Zimmerman with "blood on the back of his head," he told police. Zimmerman allegedly told the witness that Martin "was beating up on me, so I had to shoot him." In two interviews after that one a month later, the witness described Zimmerman's demeanor as nonchalant, "... More like, 'Just tell my wife I shot somebody' like it was nothing."

The witnesses are expected to be interviewed at least once more before Zimmerman's trial.

This week, security video was released showing Trayvon Martin at a Sanford, Fla. 7-Eleven the night he died. The teen purchased a bag of Skittles and an Arizona iced tea, a short time before he was killed.

The evidence from that night -- and the dialogue surrounding it -- has grown increasingly complex. Last week, it was revealed that Zimmerman really did sustain injuries to his face and head during the incident. In addition, information from Martin's autopsy report was leaked just one day after medical records from Zimmerman's family physician were released.

ABC News reported that the teen had traces of THC, the drug found in the marijuana plant, in his system the night of the shooting.

Zimmerman has been charged with shooting 17-year-old Trayvon Martin on the evening of Feb. 26 in a gated community in Sanford, Fla. Zimmerman, a neighborhood watch volunteer called 911 and told a police dispatcher that the teen, who was returning from a trip to a nearby convenience store, "looked suspicious." After an altercation, Zimmerman shot Martin in the chest, subsequently telling local police that he acted in self-defense.

This post has been updated with details about the evidence and the February incident.

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  • A photograph of George Zimmerman taken the night he shot and killed Trayvon Martin in Sanford, FL.

  • The gun George Zimmerman used to shoot Trayvon Martin can be seen in this evidence photo.

  • George Zimmerman's gun and clip can be seen in this evidence photograph taken by Sanford police. Zimmerman shot and killed Martin after an altercation with the unarmed teen, who was returning to the house where his father was staying on February 26 after a trip to a nearby 7-Eleven.

  • George Zimmerman photographed by police the night he shot and killed Trayvon Martin in a gated community in Sanford, FL.

  • Cuts can be seen on the face of George Zimmerman in this photo taken by police on the night he shot and killed Trayvon Martin. Zimmerman claims that Martin attacked him and banged his head repeatedly on the ground, prompting Zimmerman to shoot the teenager in self-defense.

  • Cuts can be seen on the face of George Zimmerman in this photograph taken the night he shot and killed Trayvon Martin. Zimmerman says he shot Martin during an altercation in which Martin slammed his head repeatedly into the ground.

  • George Zimmerman, photographed by police on the night he shot Trayvon Martin in Sanford, FL.

  • Blood can be seen on the head of George Zimmerman in this police photo taken the night he shot and killed Trayvon Martin. Zimmerman claims he shot Martin, an unarmed teenager, in self-defense.

  • Blood can be seen on the head of George Zimmerman in this police photo taken the night he shot and killed Trayvon Martin.

  • Blood and bruises can be seen on the head of George Zimmerman in this police photo taken the night he shot and killed Trayvon Martin.

  • In this Feb. 27, 2012 image taken from a Sanford Police video posted on a website called by George Zimmerman'sdefense team, Zimmerman speaks to investigators, (not shown) at the scene of Trayvon Martin's fatal shooting a day later giving police a blow-by-blow account of his fight with the teen. On the tape, Zimmerman did a reenactment of the scuffle with Martin in the moments before he shot the 17-year-old from Miami. (AP Photo/Sanford Police video via Zimmerman Defense Team)

  • This photo released by the Seminole County Sheriff's Office shows Shellie Zimmerman. Zimmerman, the wife of the Trayvon Martin shooter George Zimmerman, was charged with perjury and accused of lying when she told a judge that the couple had limited funds during a hearing that resulted in her husband being released on $150,000 bond. She was released on $1,000 bond. (AP Photo/Seminole County Sheriff's Office)