Wayne Circuit Judge Cynthia Gray Hathaway announced her decision after jurors said they could not reach a verdict after deliberating for three days in the involuntary manslaughter trial of Joseph Weekley, who shot Aiyana Stanley-Jones during a May 2010 search for a suspect, The Detroit News reported.
Weekley -- a member of the Detroit Police Special Response Team -- was also charged with reckless discharge of a firearm causing death.
Weekley was searching for a man suspected of shooting and killing a teen when he entered a home where Aiyana was asleep with her grandmother, Mertilla Jones, on a sofa. A shot from his MP-5 submachine gun struck the girl and killed her, but Weekley testified he was unaware his gun discharged.
After the mistrial was announced, Aiyana's mother, Dominika Stanley, joined other family members outside the courtroom, where Jones called Weekley a liar for claiming she touched his weapon at one point, the Detroit Free Press reported.
"I think it's sad that grown people can't make up their mind that this cop murdered my 7-year-old granddaughter," Jones said.