Four key witnesses for George Zimmerman, the man who shot and killed teenager Trayvon Martin in February, made major charges to their stories of the incident in what could be a key moment in the second-degree murder case.

According to The Orlando Sentinel, the witnesses were reinterviewed in mid-March after Sanford, Florida police turned the case over to State Attorney Norm Wolfinger. A young woman identified as witness number two altered her original story of seeing two guys running close to each other in the dark to seeing just one person running and hearing him more than she saw him.

A young mother identified as witness number 12 was originally unsure whether Zimmerman or Martin were on top of one another on the ground after the shooting. However, six days later she was definitive on Zimmerman being the one on top.

Witness number six was a man who originally indicated that Martin was on top of Zimmerman and punching him in the face while Zimmerman called for help on the ground. Three weeks later, the man stated he was now uncertain on if Martin was throwing punches or keeping Zimmerman on the ground, but did continue to say Martin was on top.

A fourth person identified as witness number 13, who came outside his house to observe what happened, talked to Zimmerman after the shooting and analyzed his behavior.

The man originally said that Zimmerman had a shocked reaction toward shooting Martin, saying he "was beating up on me, so I had to shoot him" and told him to call his wife Shellie Zimmerman about what happened. However, in his second account, witness number 13 said that Zimmerman was rather nonchalant about shooting Martin.

All four witnesses will be interviewed again before the trial begins.