One of the hardest-working officers involved in the manhunt for two Colorado fugitives along the San Juan River sneaks through the bushes on four legs and answers to the name of Missy.

A one-year-old border collie, Missy is a search dog for the Duchesne County Sheriff's Office. She and her master, sheriff's Sgt. Wally Hendricks, have made six separate trips to the Four Corners since June 4 to help with the search for Alan "Monte" Pilon and Jason Mc-Vean, the men police believe shot and killed a Colorado police officer May 29, triggering the 45-day manhunt across the region.Missy revels in her work, Hendricks said. "She loves it, and she will not quit," he said, resting under a shade tree while waiting for a search assignment Saturday. "She's worked a 10 1/2-hour day in 110-degree heat, and she just wants to keep going."

About 90 percent of the work, Hendricks said, has been to either eliminate or substantiate leads found in the river bottoms. The thick foliage, rocky terrain and high temperatures have made the job tough.

"It's physically very taxing on everyone," he said, adding that last week several officers collapsed from heat exhaustion. "I've been trying to keep her well-hydrated and rested."

Missy starts a search day with a breakfast that includes watermelon-flavored Gatorade, Hendricks said.

"My vet actually recommended it, and it works very well," he said.

Hendricks will continue to feed, water and even mist Missy's paws with water throughout the day. When quitting time comes, the four-footed tracker winds down with a glass of V8.

Under perfect circumstances Missy would be starting her daily search work by getting a sniff of a hat, piece of clothing or other article of the suspect or missing person before beginning her foray into the brush. But police haven't really had those kind of leads, Hendricks said. So mostly, Missy has tracked footprints and scents lingering on bushes or at possible campsites.

"There have been so many people down on the river, it's tough. There are lots of smells,' he said.

But Missy's eyes light up and her tail gets wagging when she's on to a track, Hendricks said.

"If she hits a track, you see a change in her behavior. She's intently focused," he said.

Hendricks and Missy have been training as a search team for the past several months. Hendricks got interested in raising a track dog after working with a Salt Lake area-based volunteer search and rescue dog group that came to Duchesne County to help with a search. The two spend about 15 hours a week working on search skills.

Most of what Missy does in finding something or - in this case - someone is instinctive. Through training Hendricks helps Missy associate certain behavior with certain commands.

"About 90 percent of it is actually us learning about the dog, reading the dog's behavior," he said.

In addition to using Missy in searches, Hendricks has put her to use in Duchesne County criminal work. She successfully tracked two men who had ransacked and robbed an elderly woman's home one Sunday morning. "She got on a scent and took off. When I rounded a corner to catch up with her, there they were petting her," Hendricks said chuckling. "Then they realized she wasn't just a dog."

Too bad nabbing fugitives Pilon and McVean isn't quite that easy, he said.