George Zimmerman's defense attorneys have talked to the former lead investigator in the case.

Court documents from Seminole County show defense attorneys have conducted depositions from several investigators with the state attorney's office, as well as Chris Serino, the now-former Sanford police detective who led the investigation into the shooting death of Trayvon Martin nearly one year ago.

Defense attorneys said Serino recommended that Zimmerman be charged in Martin's death, even after the Sanford Police Department came to a consensus that, at the time, there was no case against Zimmerman.

Serino is expected to be a key witness in Zimmerman's trial for second-degree murder. Former Casey Anthony attorney Jose Baez is representing Serino.

Zimmerman has claimed he was defending himself with he fatally shot Trayvon Martin on Feb. 26, 2012, saying the 17-year-old attacked him and citing Florida's so-called "Stand Your Ground" law in his use of deadly force.