Sheriff's officials announced at a 4 p.m. news conference that they believed Dorner's death was the result of a self-inflicted gunshot wound.
McMahon stressed early in the news conference that his department has nothing to hide and he is confident in its actions during their search for Dorner.
The sheriff also said the manhunt is over in reference to Thursday's announcement that Dorner's body was found inside a cabin in Barton Flats.
"We can now begin the healing process," McMahon said.
McMahon said Tuesday's mayhem started when deputies discovered shoe prints in the snow leading to the cabin. Dorner, 33, then ambushed initial responding officers and began firing at them, McMahon said.
Detective Jeremiah MacKay and his partner Alex Collins were the first two deputies on scene. MacKay, 35, of Redlands was killed and Collins was seriously wounded.
"Both officers went down," he added.
Other sheriff's deputies responded and went through a "hail of gunfire" to rescue the injured officers and dragged them back to cover, McMahon said.
Deputies then traded gunfire with Dorner.
"When we would move, he would shoot at us," McMahon said.
During the gun battle, deputies made multiple announcements calling for Dorner to surrender.
When Dorner still refused to respond, officials deployed pyrotechnic chemicals.
McMahon justified the deputies' actions by saying the hot gas was the only option to get Dorner out of the cabin since the cold gas did not work.
At the same time, deputies said they believed Dorner was throwing smoke inside the cabin to obscure the view of deputies.
A fire broke out in the cabin and, as the flames spread, officials heard a "distinct single gunshot come from within the house," Capt. Gregg Herbert said. Sheriff's officials said they believe Dorner likely shot himself.
"The cabin was consumed by fire to the point where it was not a structure anymore," he said.
Eventually, SWAT members pulled back and the scene was turned over to homicide detectives.
Later that night, after the flames had smoldered, authorities discovered a body inside the cabin.
Capt. Kevin Lacy informed media that after a 6-hour autpopsy, officials identified Dorner through dental records.
He also revealed Dorner's cause of death - a single gunshot wound to the head.
Lacy said the wound was likely self-inflicted, but the Sheriff's Department is not ready to confirm a suicide.
Authorities also announced that they found several weapons and tactical gear recovered from places occupied by Dorner.
Numerous assault weapons and semi-automatic hand guns, a tactical-style load bearing vest, gas canisters, high-capacity magazines, a military-style Kevlar helmet and 10 silencers were located at several scenes throughout the mountain, McMahon said.
When reporters were allowed to ask questions, many of them focused on comments made by authorities during the gun battle and the empty cabin Dorner hid in that was in close proximity to a command post.
McMahon said he will look into comments heard on a police radio about intentionally burning the cabin down, but he does not believe it was attributed to those involved in tactics.
The deputies involved in the chaotic scene are human beings, McMahon said, and they had just been involved in one of the most "fierce firefights."
"Sometimes, because we're humans, we say things that may or may not be appropriate," McMahon said.
McMahon also acknowledged that Dorner may have been in a residence on Club View Drive when deputies knocked on its door Thursday.
McMahon said his deputies were not going to kick the doors open on hundreds of cabins if there was no sign of forced entry.
Officials found nothing unusual and said the door was locked. Deputies put evidence tape near that cabin to show it had been checked and moved on with their search.
"They did a good job checking the neighborhood," McMahon said.
The press conference lasted about 30 minutes. McMahon ended it by saying the investigation is over as far as San Bernardino County is concerned and it is now in the hands of other agencies.