Trayvon Martin's girlfriend, who was on the phone with him before the unarmed teen was shot and killed by George Zimmerman, will testify before a grand jury. The grand jury will be impaneled April 10 to determine if Zimmerman, the neighborhood watch captain, should be charged with murder, according to reports. The Trayvon Martin case gained national attention after he was gunned down by Zimmerman, who felt he was acting suspiciously in his ...