By Barbara Liston
SANFORD, Florida (Reuters) - A Florida judge on Tuesday ruled out any further delay in next month's trial of George Zimmerman, the former neighborhood watch captain charged with second-degree murder for last year's killing of unarmed black teenager Trayvon Martin.
Circuit Court Judge Debra Nelson, who ruled against several key defense motions during a two-hour hearing in Seminole County Criminal Court, rejected a defense request to delay the scheduled June 10 start of the trial.
Martin's February 26 2012 killing ignited protests across the country. Much of the public outcry centered on race issues in America because police initially declined to arrest Zimmerman, who is white and Hispanic, on grounds that he killed the 17-year-old Martin in self-defense.
During Tuesday's hearing, Nelson ruled that defense attorneys cannot bring up Trayvon Martin's past marijuana use at trial, or his school suspension shortly before he was killed and alleged participation in fights.
Such background information might only be addressed during the trial if its relevance became apparent during the proceedings and the judge gave specific permission to use it, Nelson said.
She also barred lawyers from mentioning, in their opening arguments, that an active ingredient of marijuana was found in Martin's blood shortly after his death.
Nelson also denied the state's motion for a gag order in the case and said she would rule at a later date as to whether the jury should be sequestered.
In an unexpected matter, Nelson scheduled a separate hearing for this Friday to address a claim by Zimmerman's lead defense attorney, Mark O'Mara, that some evidence, including three photos Martin downloaded from his cellphone, had been withheld from him by the prosecution.
A defense request that jurors be taken to the crime scene, in a gated community in this town near Orlando in central Florida, was also rejected by Nelson.
In a motion to ban evidence of marijuana use, prosecutors said there is no evidence that Martin was under the influence or that marijuana contributed to his death. O'Mara claims, however, that the evidence supports the defense theory that Martin was the aggressor.
Zimmerman followed Martin after he spotted him walking in the rain in the gated community in Sanford, where Martin was spending the weekend in one of the town homes with his father. Zimmerman called police to report a suspicious person and pursued Martin despite the dispatcher telling him not to. Soon after, Zimmerman shot Martin during a struggle before police arrived.
In court filings Zimmerman's lawyers say they want the judge to decide about the use during the trial of voice analysis of 911 tapes of calls to the police before and during the struggle.
Lawyers are seeking clarification from the judge about whether the science behind the various types of voice analysis used by experts for the state and defense is solid enough to be considered by the jury.
Nelson said those issues would be addressed at final pre-trial hearings sets for June 6-7.
Experts have reached different conclusions about whether it was Zimmerman or Martin screaming in the background of a 911 call taped just before Martin was shot, or whether it is possible to be certain at all.
Some experts could isolate only seconds of usable audio on the tape while one prosecution expert claims to have deciphered several phrases uttered by Zimmerman and Martin.
(Editing by Tom Brown and Nick Zieminski)