TULSA, Okla. — Several members of an Oklahoma sheriff’s department raised serious concerns years ago about the performance and training of a volunteer deputy now charged in the fatal shooting of a restrained suspect, according to a report released by lawyers for the dead man’s family.

Lawyers for Eric Harris’ family on Friday released a Tulsa County Sheriff’s Office memo outlining an investigation into Robert Bates, 73. Bates says he confused his handgun for his stun gun during an April 2 sting involving gun sales and has pleaded not guilty to second-degree manslaughter in Harris’ death.

Bates is a longtime friend to Sheriff Stanley Glanz, serving as his insurance agent for 25 years and his re-election campaign manager in 2012. Bates is white and Harris was black, but the victim’s brother has said he doesn’t believe the shooting was racially motivated.

The 2009 report says Bates, who had joined the Tulsa County Sheriff’s Office less than a year earlier, had argued with a dispatcher, improperly used a personal vehicle on the job and had inadequate training for a role as an advanced reserve deputy.

It concludes that Bates didn’t receive special treatment by being admitted to the program because no advanced deputy had fully met internal standards. However, it found he did receive special treatment in other ways, including department leaders’ ignoring complaints about his performance.

Meredith Baker, an attorney for the sheriff’s office, said Friday that no action was taken as a result of the report, but that the document’s existence “demonstrates this office’s willingness to investigate and review any allegations of policy violations.”