Weeks after high school junior Trayvon Martin was shot and killed by a neighborhood watch volunteer in Sanford, Florida, the police are now prepared to release the 911 tapes to the public.

Despite knowing that George Zimmerman, the volunteer, shot the unarmed 17 year old, police have made absolutely no arrests in the case. Zimmerman, 28, has claimed self defense and Sanford Police Chief Billy Lee says, “Until we can establish probable cause to dispute that, we don’t have the grounds to arrest him.”

If you aren’t up on the case, here is some background information:

Martin had been staying at his father’s girlfriend’s house during the night of the NBA all-star game Feb. 26.

On his way back into the gated suburban Orlando community after stepping out, Martin, wearing a hood, was spotted by Zimmerman.

According to law enforcement sources who heard Zimmerman’s call to a non-emergency police number, he told a dispatcher “these a**holes always get away.”

Zimmerman described Martin as suspicious because he was wearing a hooded sweatshirt and walking slowly in the rain, police later told residents at a town hall.

A dispatcher told him to wait for a police cruiser, and not leave his vehicle.

But about a minute later, Zimmerman left his car wearing a red sweatshirt and pursued Martin on foot between two rows of townhouses, about 70 yards from where the teen was going.

Witnesses told ABC News a fistfight broke out and, at one point, Zimmerman, who outweighed Martin by more than 100 pounds, was on the ground and that Martin was on top.

Austin Brown, 13, was walking his dog during the time of the altercation and saw both men on the ground but separated.

Brown, along with several other residents, heard someone cry for help, just before hearing a gunshot. Police arrived 60 seconds later and the teen was quickly pronounced dead.

According to the police report, Zimmerman, who was armed with a handgun, was found bleeding from the nose and the back of the head, standing over Martin, who was unresponsive after being shot.

Trayvon had no criminal record, but it turns out that Zimmerman does. In 2005, he was charged with resisting arrest and battery of an officer.

Martin’s parents want the 911 tapes released because during several of the calls for help, shots can be heard in the background.

But police have now decided to release the tapes in hopes that they will calm down “the high state of emotions” surrounding the case. Many believe Zimmerman hasn’t been arrested because Trayvon was a black boy confronted by a white man.

The teen’s family and community also think police have botched the investigation by failing to properly question Zimmerman and correcting the story of a witness.

Trayvon’s father, Tracy Martin, says the lack of arrests and movement in his son’s killing is “surprising. It’s shocking. It lets me know that justice is just not being served here. All we want is justice for our son. We’re not asking for anything out of the ordinary.”

Sanford mayor Jeff Triplett and U.S. Representative Corrine Brown will be asking to meet with U.S. Attorney General Eric Holder next week.

Sybrina Fulton, Trayvon’s mother, and his father have started a petition on Change.org to move forward a full investigation of their son’s death.

Sources: Orlando Sentinel; ABC News