The lawyer for the family of an African-American teenager shot and killed by a neighborhood watch volunteer in Florida says they have information disputing the man's claim that he shot the boy in self-defense.

Benjamin Crump told reporters Tuesday that records of calls from Trayvon Martin's mobile phone shows the boy was talking to his girlfriend moments before last month's fatal shooting. Crump says he learned from the girl that Trayvon noticed he was being followed as he was walking back home from a convenience store near Orlando.

According to the lawyer, 17-year-old Trayvon ran away at his girlfriend's urging, and manages to briefly evade the man. The girlfriend urged Trayvon to run again, but the teenager said he was just going to walk fast. Trayvon then asks the man why he is following him, followed by the older man demanding to know what Trayvon is doing in the neighborhood. A few minutes later, Crump says the girl heard what sounded like Trayvon being pushed, followed by an altercation, before the phone cuts off.

Moments later, police arrived on the scene to find Trayvon had been shot by George Zimmerman, who had called emergency personnel before the shooting to report a suspicious person in the neighborhood that turned out to be Trayvon.

But Crump says Zimmerman's claims do not hold up under the girl's recollection.

“Never in any account other than George Zimmerman, this neighborhood association 'loose cannon,' does anybody say that Trayvon Martin was up to no good, that he seemed high, or anything, and in fact, this young lady details completely the tone of the conversation and the nature of the conversation, and what was happening the last minutes of his life.”

Zimmerman has not been arrested by local police, which has sparked outrage among African-Americans nationwide in recent days. Prosecutors in Florida announced Tuesday they will convene a grand jury to investigate the incident, a day after the U.S. Justice Department said its civil-rights division is opening an investigation.

The incident has also drawn attention to so-called “stand your ground” laws in Florida and several other states, which allows people to confront a potential attacker with deadly force if they feel their life is in danger.