Judge In Zimmerman Trial Bars Audio Experts' Testimony : The Two-Way The ruling says experts used unproven methods to determine that screams heard on a 911 call came from Trayvon Martin.

Judge In Zimmerman Trial Bars Audio Experts' Testimony

Judge Debra Nelson addresses concerns from the state and defense during a pretrial hearing on Friday. Pool/Getty Images hide caption

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A judge in the murder trial of George Zimmerman has excluded testimony from two audio experts who've suggested that Trayvon Martin can be heard screaming on a 911 call moments before the unarmed teen was fatally shot.

Judge Debra Nelson issued the 12-page ruling on Saturday after hearing days of arguments on whether to allow the testimony.

The Associated Press says one expert ruled out Zimmerman as the screamer and another said it was Martin. Defense experts argued there was not enough audio to determine whom the screams are coming from.

The Miami Herald described the ruling as a "major blow" to prosecutors:

"The testimony of Tom Owen and Alan Reich, both of whom analyzed a 911 call by a neighbor that captured the sounds of the brawl, was key for the state because it could have painted Zimmerman as the aggressor."

"There is no evidence to establish that their scientific techniques have been tested and found reliable," Nelson wrote.

The newspaper added that the judge:

"... singled out Reich, who claimed he heard Trayvon saying specific phrases, including 'I'm begging you.' Nelson said his report to the prosecution, which differed from one given earlier to a newspaper, 'would confuse issues' and 'mislead the jury.' "

Zimmerman, a neighborhood watchman, is accused of shooting Martin during a February 2012 scuffle inside a gated community in Sanford, Fla.