George Zimmerman (left, 2005 mug shot) and Trayvon Martin (family photo)
(CNN) -- As outrage over the killing of Florida teenager Trayvon Martin continues to spread online, social media and news outlets are debating whether the shooter uttered a racial epithet in one of his 911 calls. And if so, what he might have said.
Zimmerman, whom authorities described as white and family members say is Hispanic, said he shot 17-year-old Trayvon Martin in self-defense, according to police. Martin, who was black, was walking to his father's fiancee's house in Sanford, Florida, after a trip to a convenience store and was not armed.
Many people at CNN have listened repeatedly to the call but have been unable to reach any consensus on what was said. An audio engineer enhanced the sound on the 911 call but said it was difficult to improve the quality or to replicate the background noise. CNN continues to analyze the tape and consult outside experts.
Sanford police haven't confirmed what was said on the recording but deny a news report they overlooked a racist remark during the investigation.
"I said we didn't hear it; however, I am not sure what was said," Sanford Police Sgt. David Morgenstern told CNN. "So I never said we missed a racist remark.
"I'm not sure what was said. I heard something, but again, not clear as to what was said. I did not hear it until it was pointed out to me."
In the full 911 call above, the alleged slur comes just after 2:20.
Tell us in the comments: Do you hear a racial slur?
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Trayvon Martin's death renews Stand Your Ground debate
More than 400,000 sign Trayvon Martin petition
Trayvon Martin's parents call for FBI probe
Trayvon Martin's death gains national attention
Trayvon Martin: Protestors rally at Florida capitol
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