Bergan had previously lived in Florida before returning to Norway, where he lived with Dennis's daughter and their young son.
Speaking at a news conference on Thursday, the sheriff told reporters Dennis would not be charged over the incident.
"Our investigation has revealed that this was totally accidental, it was a really sad occurrence, and that no charges are warranted in this case," Johnson said.
Amber Roland, a lawyer with the State Attorney's Office, said authorities had examined the scene of the tragedy.
"We were able to view the evidence," she said.
"We were present on scene when detectives interviewed the witnesses.