CHARLOTTE, NC (WBTV) - It appears a breach of safety protocol was a factor in the death of Charlotte Mecklenburg Police Department SWAT team veteran Fred Thornton.
The police department has released details of it's preliminary investigation.
Officer Thornton, a 28-year CMPD veteran and most tenured member of the SWAT team, was killed on February 25 when a "flash bang" exploded in the garage of his Mint Hill home.
CMPD says Thornton's team was called to serve a search warrant earlier in the day in north Charlotte. Thornton's job was to go to the rear of the home and deploy, at his discretion, a Flash Sound Diversionary Device (FSDD), or "flash bang."
Investigators believe he was ready to use the FSDD and pulled the cotter pin, to activate it, but he decided not to release it.
Investigators say CMPD SWAT training and procedures dictate "that if the cotter pin is pulled; the device should be activated by throwing the FSDD into a safe location."
Thornton did not activate the device. Investigators believe he "reinserted one 'leg' of the cotter pin back into the device" making it stable.
CMPD says "reinsertion of the pin is not an authorized technique."
The report says Thornton returned to the SWAT office for a debrief and then headed home.
Investigators think he removed the pin again in his garage and when attempting to replace it one more time, it went off.
CMPD says while the investigation has not determined why the FSDD activated, it is believed the device was stable until the cotter pin was removed.
CMPD continues to use the same flash bang devices as it has for the past five years.
Investigators say "there are no reasons to believe, or evidence to suggest the device safety features failed."
Thornton is survived by his wife and four children.