OKLAHOMA CITY -- A volunteer law enforcement officer was booked into jail Tuesday on a manslaughter charge in the death of an Oklahoma man who was fatally shot as he lay on the ground at the officer's feet.
The sheriff's office has said Robert Bates, a 73-year-old insurance executive who was volunteering on an undercover operation, mistakenly pulled out his handgun instead of his stun gun and shot Eric Harris as the suspect struggled with deputies.
It was the latest fatal shooting by a police officer to draw national attention after months of investigations and protests of other deaths in Ferguson, Missouri, New York City, South Carolina and elsewhere.
Many of the cases have stirred debate about the treatment of black men and boys by U.S. law enforcement agencies. Bates is white and Harris, 55, was black. But at a news conference Monday, Andre Harris, the Oklahoma victim's brother, said he does not believe that shooting was racially motivated.
The Oklahoma case, however, has raised questions about the use of volunteer officers to supplement full-time police.
Bates was charged Monday with second-degree manslaughter involving "culpable negligence" for Harris' April 2 death. If convicted, Bates could face four years in state prison, reports CBS News correspondent Elaine Quijano.
Bates surrendered to the Tulsa County Jail and was released after posting bond. Bates' attorney, Clark Brewster, told reporters that his client would not make a statement.
A video of the incident shot by a deputy with a sunglass camera and released Friday at the request of the victim's family, shows a deputy chase and tackle Harris, who they said tried to sell an illegal gun to an undercover officer.
As the deputy subdues Harris on the ground, a gunshot rings out and a man says: "Oh, I shot him. I'm sorry."
Harris screams: "He shot me. Oh, my God," and a deputy replies: "You f---ing ran. Shut the f--- up."
When Harris says he's losing his breath, a deputy replies, "F--- your breath."
Harris was treated by medics at the scene and died in a hospital.
The family said in a statement Tuesday that it applauded the filing of criminal charges but added: "There remain many unanswered questions. And we will continue to fight until those questions are answered."
Earlier, the family said it was "saddened, shocked, confused and disturbed."
"These deputies treated Eric as less than human. They treated Eric as if his life had no value," the family wrote.
The use of reserve officers is commonplace across much of the U.S. Cities and counties often turn to them for extra manpower because of a lack of resources and tight budgets.
Reserve deputies are permitted to carry firearms but have far less training than regular officers.
Bates, who was briefly a full-time officer with the Tulsa Police Department from 1964 to 1965, updates his certification every year, said Tulsa County sheriff's spokesman Shannon Clark.
CBS affiliate KOTV reports that Andre Harris, the victim's brother, believes Bates was allowed to be a reserve deputy because he made some generous donations to the Tulsa County Sheriff's Office.
Tulsa County Sheriff Stanley Glanz has described Bates as a personal friend, and records show he has been a generous donor to the department since he became a reserve deputy in 2008.
Besides a $2,500 donation to Glanz's re-election campaign in 2012, records released on Monday by the sheriff's office show Bates donated five vehicles, a computer and forensic camera and a hand-held radio to the department from 2009 to 2011.