On Aug. 23, while investigating a crash in the eastbound corridor of Interstate 80 in Parley's Canyon, Dunn was struck by a utility truck as he was getting something out of his squad car. The driver drifted into the right lane, which was blocked off as troopers investigated a crash between a minivan and a semi-trailer.
Trooper Chamberlin Neff, who also was investigating the first crash, said he heard the truck hit Dunn's car, but didn't see it. When he went to see what had happened, he saw Dunn, his commanding sergeant, leaning against his car. There was blood everywhere.
Neff soon discovered the blood was coming from a large cut in Dunn's forearm and the severed portion of his hand. Neff told him what happened.
"He said, 'You need to find my wedding ring,'" Neff said.
The hand was easier to find: It landed right between Dunn's and Neff's cars after it hit Neff's back windshield.
"It looked like someone had taken a tennis ball, soaked it in blood and threw a fastball into the back of my car," Neff said.
What happened next was fortunate blend of serendipity and skill. The severity of the first crash required an incident management truck, which just happened to have a cooler full of water bottles. One of the truck's drivers emptied the cooler and other troopers filled it with ice packs from their first aid kits. The troopers then put Dunn's hand in an evidence bag and kept it on ice.
Meanwhile, the training the troopers had recently received on applying tourniquets was suddenly relevant. The training earlier this year involved a new type of tourniquet designed for severe injuries such as Dunn's. Thanks to that training and the right tourniquets on scene, the troopers were able to quickly stop the bleeding from Dunn's hand, Neff said. They also were able to patch up a large cut on his forearm before medical responders arrived.
"It was great training, and it obviously showed with Chris' situation," Neff said.
Dunn was taken by helicopter to University Hospital, and after more than eight hours of surgery, his severed hand was finally reattached. Only then did he finally look at it.
And he got his wedding ring back, too.
Dunn was back on the job this week, although he works only four hours a day mostly doing paperwork at the office. It could be a while before he gets back on patrol, and right now he's taking things one day at a time. He goes to physical therapy three times a week.
"It's slow," he said. "I can't do anything with my hand right now."
There is some progress, though. He can move his fingers, although he can barely feel them. Doctors tell him it will take a few months for the nerves in his hand to fuse properly.
"We just hope for the best," Dunn said.
In his 14 years with the UHP, this was Dunn's first major injury. It's been a reminder of just how dangerous his job can be.
"That's as close to death as you can come," he said. "I think about it a lot, and I count my blessings that I'm still here with my wife and my sons. And life goes on."