(Reuters) - The case of an unarmed black teenager shot dead by a white neighborhood watch captain who police have failed to arrest will go before a grand jury, Florida prosecutors said on Tuesday. 

State prosecutor Norm Wolfinger made the announcement as the victim's family lawyer said 17-year-old Trayvon Martin was on his cellphone with a girlfriend, giving her a chilling, minute-by-minute account of what was happening in the moments before he died.

 

Police in the central Florida town of Sanford where Martin was gunned down have not arrested neighborhood watch volunteer George Zimmerman. They did not return phone calls on Tuesday seeking comment on the case, which has sparked widespread public outrage since the release of 911 emergency tapes last week.