Oklahoma judge orders grand jury investigation of Tulsa sheriff's office
Tulsa County reserve sheriff's deputy Robert Bates appears on NBC's 'Today Show' on April 17, 2015.

An Oklahoma judge on Tuesday ordered a grand jury investigation into the Tulsa County Sheriff’s Office, which has been under scrutiny since a white reserve sheriff's deputy fatally shot a black suspect in April.

Judge Rebecca Nightingale issued the order after an activist group submitted a petition aimed at compelling a grand jury investigation into Sheriff Stanley Glanz and his department.

The judge ruled that the petition complied with state laws and rejected a request for dismissal from Glanz, who argued the signatures were collected on "homemade forms."

A community civil rights group called "We the People Oklahoma" submitted the petition on June 19 with more than 8,800 signatures calling for the probe into Glanz and the sheriff’s office.

Under Oklahoma law, if at least 5,000 of those signing the petition are verified as registered voters, a judge can summon prospective members of a grand jury within 30 days.

The request stems from allegations of special treatment, questionable reserve officer training and falsified records made in the aftermath of the April 2 death of Eric Harris, the group said.

The department has denied the allegations.

Robert Bates (pictured above), a 73-year-old reserve deputy, has been charged with second-degree manslaughter for shooting Harris, 44. Bates thought he was using a Taser instead of his gun, the Tulsa sheriff's office said of the incident that was videotaped and shown in the media.

The case was one of many in recent months that raised questions about the role of race in U.S. policing.

The Tulsa County Sheriff's Office is also under investigation by the Oklahoma State Bureau of Investigation, which is looking into possible misconduct.

(Reporting by Lenzy Krehbiel-Burton; Editing by Jon Herskovitz and Peter Cooney)