Updated

Prompted by the fatal shooting of an unarmed man during a sting operation, a civil rights group said Tuesday it has collected enough signatures for a grand jury to investigate Tulsa County Sheriff Stanley Glanz and the agency's reserve deputy program.

Marq Lewis, an organizer of We the People Oklahoma, told The Associated Press in an interview that his group has so far gathered more than 6,000 signatures from registered county voters to authorize an order to impanel a grand jury.

The group needed 5,000 under state law, and Lewis said he plans to file the signatures with officials sometime this week to certify the names. Lewis said they'll keep collecting signatures until then.

"We had asked Glanz to step down, but this is actually the only recourse as citizens we had," Lewis said. "I don't think they actually thought we were going to go through with it."

The petition asks the grand jury to investigate whether Glanz neglected his duties and whether reserve deputies who gave donations to the sheriff were given special treatment.

Robert Bates, the reserve deputy who has pleaded not guilty to second-degree manslaughter in the April 2 shooting death of Eric Harris, is a friend of Glanz. He has donated tens of thousands of dollars in cash and equipment to the sheriff's office.

Bates has said he confused his handgun and stun gun in the shooting. Bates is white; Harris was black. The victim's brother has said he does not believe race played a role.

The Oklahoma State Bureau of Investigation is already investigating the shooting after a leaked 2009 memo raised concerns about Bates' training. The reserve deputy program also has been temporarily suspended pending a review of the certification and training records of its 126 reservists.

Glanz, who took office in 1989, has said that he won't step down because of the shooting, but that he also wouldn't seek re-election next year.

Terry Simonson, a spokesman for the sheriff's office, said in a recent interview that Glanz would welcome the grand jury investigation so he can tell his side of the story.

"You have not heard him talk much about what he knows or some of the people who work for him, but put him in a room that's closed to the public with the district attorney and 12 citizens, he is absolutely confident ... the truth will win," he told AP. "(Glanz) says, 'I know what I did. I know what I know. I know I can explain it. It may not make good print, but it makes good truth.'"