CHARLOTTE, N.C. — After nearly four days of jury deliberations, a judge declared a mistrial on Friday in the trial of a white Charlotte police officer who killed an unarmed black man almost two years ago.

Judge Robert C. Ervin brought the jury of eight women and four men back into the courtroom shortly after 4 p.m., and the foreman said he saw no possibility of a verdict in the case against Officer Randall Kerrick, who was charged with manslaughter in the fatal shooting of Jonathan Ferrell.

“We have exhausted every possibility short of calling in the paramedics,” the foreman said, an apparent reference to the intensity of the discussions.