Georgia Ferrell says she's still seeking justice after a jury couldn't unanimously decide the fate of a white North Carolina police officer accused in the 2013 shooting death of her son, an unarmed black motorist.

"I've got to keep fighting," Ferrell said outside a courthouse late Friday afternoon after she heard a judge declare a mistrial in the voluntary manslaughter case of Charlotte-Mecklenburg police officer Randall Kerrick. "We must get justice."

A racially diverse jury of eight women and four men deliberated over four days. It took four votes without reaching unanimous agreement in the death of Jonathan Ferrell, a former Florida A&M football player.

Prosecutors must now decide if they want to try Kerrick a second time. Kerrick's defense lawyers had no comment afterward.