Was Trayvon Martin called a racial slur before being killed?

I've pretty much stayed away from posting on this story as I always thought justice would be done...but things have gotten way out of hand.  Tonight there are new reports about racial slurs which George Zimmerman supposedly uttered under his breath and were heard on the 911 tape indicating a police cover up.

So here's the link for the tape. You be the judge.

George Zimmerman: Did He Call Trayvon Martin A "F---ing Coon" Before Killing Him?
 Story by: IBTIMES STAFF REPORTER
As outrage builds over last month's fatal shooting of 17-year-old Trayvon Martin by George Zimmerman, a Florida self-identified neighborhood watchman, police are coming under fire for missing a possible clue in the investigation: a racist remark that shooter George Zimmerman may have muttered under his breath just moments before he shot and killed Trayvon Martin.

According to ABC News, George Zimmerman may have muttered "f***ing coons" as he pursued Martin while he was on the phone with 911. Sirius XM radio talk host Joe Madison claims to have enhanced the publicly available 911 recording and posted it on his website, which indeed does sound very similar to the alleged racial slur.

Story and link here