(FOX 9) - How does a veteran police officer unintentionally fire her handgun mistaking it for her Taser stun gun?
It is one of the troubling questions investigators and prosecutors will need to answer about the killing of Daunte Wright.
"This was an accidental discharge that resulted in the tragic death of Mr. Wright," said Brooklyn Center Police Chief Tom Gannon at a press conference Monday, before submitting his resignation Tuesday.
The officer who fired her weapon, Kimberly Potter, a 26-year veteran, resigned Monday. She was charged Wednesday with second-degree involuntary manslaughter.
Protestors have been incredulous at the description of the killing of Wright as "an accident."
In police training circles its known as "slips and capture," when a police officer under stress reverts to established patterns, and unintentionally reaches for their handgun instead of their Taser.
It has happened 18 times in the last 20 years, according to a former Texas police officer who tracks cases of handgun/Taser confusion.
"All these cases have one shot, which is a big clue," said Greg Meyer, a former captain and trainer with the Los Angeles Police Department.
Unlike a firearm, a Taser fires only a single shot, attaching a wired talon carrying a disabling electrical current to a suspect.
"Their attention slips off the track and they end up drawing their handgun, which they have more practice at, and they end up firing one shot," Meyer said.
The concept of "slips and capture" has been popularized by Prof. Bill Lewinski of the Force Science Institute in Mankato, who claims to bring scientific rigor to police training. Others say he peddles pseudo-science and mischaracterizes research.
Meyer and Lewinski were both expert witnesses for the defense in the trial of Bay Area Rapid Transit Officer (BART) Johannes Mehserle, who on Jan. 1, 2009 shot and killed Oscar Grant, after reaching for his handgun instead of his Taser.
Mehserle was charged with murder, but the testimony of Meyer and Lewinski was considered key in the jury finding the officer guilty of involuntary manslaughter.
In Tulsa, a 73-year-old deputy reserve officer, Charles Bates, was also convicted of involuntary manslaughter after killing Eric Harris, 44. Bates claimed he thought he was holding his Taser.
Bates shot Harris while he was on the ground being restrained.
Meyer, who has not seen the body camera video of Wright’s killing, is cautious about drawing parallels to other cases.
"Each case must be decided on its own merit," he said.
Other experts on police use of force are skeptical of the ‘slips and capture’ concept.
"The problem is, this is impossible to test," said Seth Stoughton, a use of force expert who testified in the Derek Chauvin trial on Monday.
In a wide-ranging interview last summer about research coming out of the Force Science Institute, Stoughton described ‘slips and capture’ as pseudo-science.
"It's a theory, but you can’t look at any one incident and say, ‘Oh, that was slips and capture’ and therefore it is okay, as opposed to ‘That was a hideously unreasonable mistake and therefore it is not okay,’" Stoughton said.
Howard Williams, a former police chief in San Marcos, Texas has collected data from press reports on ‘slips and capture’ from around the country. He provided his data to the FOX 9 Investigators.
Of the 18 weapon confusion cases he has identified in the last 20 years, five cases were fatal.
Six cases led to various criminal charges of involuntary manslaughter or assault. There were only three convictions, one plea bargain, one acquittal.
According to Williams’ data, there may be a common human error in many of the cases.
In 11 cases the officer’s dominant hand crossed over, and they incorrectly grabbed a handgun where their Taser should have been.
Most officers are trained to keep their firearm on their dominant side, on the right if they are right-handed, and their Taser on their less dominant side.
"The best way Dr. Lewinski and I could come up with to prevent this is to use one hand to grab your Taser, and the other hand to get your gun, and it would greatly reduce this problem," said Meyer, the former LAPD captain.
Axon, the maker of Taser, declined to talk about the specifics of the Wright case. But in a statement to FOX 9 said, "Although very rare, there have been isolated incidents of an officer accidentally using their firearm instead of their TASER energy weapon."
The statement said the Arizona based company has taken several precautions over the years by giving the Taser a different grip, look, and feel, than a firearm and a different kind of holster.
From the body camera video, it is unclear where former Brooklyn Center Police Officer Kimberly Potter had her Taser holstered. Brooklyn Center Police did not respond to questions about the model of Taser she was using.