(CNN) -- Answers remain in short supply as to why an unarmed teenager was shot and killed two weeks ago.
Trayvon Martin, 17, was walking toward his father's home in a gated community in Sanford, Florida, around sunset on February 26.
The neighborhood watch captain, 28-year-old George Zimmerman, saw the teen on the property and called 911.
According to CNN affiliate WFTV, Zimmerman, who is white, described Martin as a suspicious black man to a dispatcher.
Sanford Police Chief Bill Lee said the 911 dispatcher told Zimmerman not to confront Martin, but by the time police arrived, the teenager lay dead with a gunshot wound in the chest. He was carrying a small amount of cash, some candy and an iced tea.
Zimmerman told police he shot Martin in self-defense, but that doesn't sit well with Martin's parents.
"When you add it up, it just doesn't even make sense," said Ben Crump, the Martin family's attorney. "Trayvon Martin, a kid, has a bag of Skittles. [Zimmerman] had a 9mm gun. Trayvon Martin didn't approach George Zimmerman, George Zimmerman approached Trayvon Martin. So how can he now assert self defense?"
Police say a gunshot can be heard on the 911 calls recorded that night.
Sanford police said Monday the calls will not be made public until the investigation is complete, but the Martin family is pushing for the tapes to be released sooner.
"It will tell us why [Zimmerman] just disregarded, just ignored the police instructions when they tell him to stay put, they'll be there in a few minutes. On those 911 tapes is going to tell you why he said he's not going to follow their instructions. And most importantly, it's going to tell us his mentality when he confronted this 17-year-old kid," Crump said.
Numerous attempts to contact Zimmerman by CNN were unsuccessful, and it is unclear whether Zimmerman has retained an attorney.
Under intense pressure from the community, city officials in Sanford held a press conference on Monday.
"We are going to complete a thorough and fair investigation and present all the information to the state attorney's office so justice can be rendered," Lee said.
Police said they have not charged Zimmerman because there are no grounds to disprove his story of what happened.
"The evidence and testimony we have so far does not establish that Mr. Zimmerman did not act in self-defense. We don't have anything to dispute his claim of self-defense, at this point, with the evidence and testimony that we have," Lee said.
Lee said the directions the 911 dispatcher gave Zimmerman to not accost Martin when the incident arose were not mandatory instructions.
"That is a call taker making a recommendation to him. He's not under a legal obligation to do that, so that is not something we can charge him with. But it would have been a good outcome if those -- if Trayvon Martin and George Zimmerman never came in contact with one another."
Tensions are swelling in the black community over why Zimmerman is free.
"You've got a little dead black boy, and the community sees you protecting the shooter," one man said.
An outraged woman said, "I'm sure you've heard the phrase, taking candy from a baby? But this person, I'm talking about every child, not just Trayvon Martin, whether he's black, white, blue, yellow or green, it is easy to take a candy from a baby. It's been said over and over and over again, but this person didn't take the candy, he took the life and left the child."
Sanford City Manager Norton Bonaparte said he had personally extended condolences to the Martin family.
"We see this as a tragedy. We are doing a full and thorough investigation, and certainly the guilty parties, where they be there, will be punished."
The report said that Zimmerman's back was wet and he was covered in grass as if he had been on the ground. He was bleeding from his nose and the back of the head, the report said.
A police officer said he overheard Zimmerman say, 'I was yelling for someone to help me but no one would help me' while he was being treated by paramedics.