U.S. Forest Service Officer James Schoeffler is trained to spot the suspicious.
He spent 12 years in the military as a bomb disposal technician dismantling deadly devices in Iraq, Afghanistan and the Balkans.
But he never expected to find the two crudely designed and potentially deadly booby traps he said he spotted last week off a popular Utah hiking trail.
Schoeffler said one was rigged to a trip wire to send a 20-pound, spiked boulder swinging at head level, while the other was designed to trip a passer-by into a bed of sharpened wooden stakes.
"It was just so out of place and so odd," Schoeffler told The Associated Press on Wednesday. "I've seen devices and booby traps all over the world, but I never thought I'd see one in Provo, Utah."
Schoeffler, a law enforcement officer with the Uinta-Wasatch-Cache National Forest, found the traps after receiving a tip about suspicious activity along a canyon trail in Provo, about 45 miles south of Salt Lake City. The area is a popular spot for families and hikers but also is known for drug activity and underage drinking, he said.
Schoeffler set out on Big Springs Trail to investigate, passing a children's birthday party and other hikers before coming across a well-known, makeshift dead-wood shelter and decided to check it out. The traps were set at entrances to the crude fort.
The first thing that struck him as unusual was fishing line strung across the ground.
"It's just something that doesn't look natural," he said.
Schoeffler, 33, surveyed the site for anything else unusual, then examined the fishing line more closely.
He traced it across the ground to a notched twig stuck in the dirt, then to the treetops, where he saw the ominous spiked boulder, which he described as medieval.
He began looking for other devices.
"Typically, anywhere I've been, if there's one, there's two, if there's three, there's four," Schoeffler said. "The way I treated that is the way I would treat a scene in a deployed environment. ... As a bomb disposal technician, you would find and disarm them."
That's exactly what he set out to do.
Within moments, he spotted the second device _ a triple strand of fishing line he said was intended to trip a person onto the bed of sharp stakes anchored deeply into the ground at about a 45-degree angle.
He said it could have been a more lethal device than the boulder.
"Impalement was a very real possibility," he said, noting the spikes could have easily stuck a throat, stomach or eye.
The discovery led to the arrest of two men over the weekend on suspicion of misdemeanor reckless endangerment. They told authorities the traps were intended for wildlife, specifically wild boar and bunnies, but investigators don't believe it.
"I wouldn't buy that excuse," Schoeffler said. "They actually used the term `bunnies.' That's kind of funny _ and there are no wild boars in Utah."
Benjamin Steven Rutkowski, 19, of Orem and Kai Matthew Christensen, 21, of Provo were booked in the Utah County Jail on Saturday and released on bail.
Prosecutors believed the misdemeanor reckless endangerment allegations were the strongest claims they could pursue without anyone having been injured. Charges have not yet been filed, and authorities said the suspects would soon be served a summons to appear in court, but no date has been set.
Rutkowski's father, Steven, declined to comment. Christensen's mother, Sharon, reached by phone Wednesday, said her son wasn't available to comment.
"I believe he told police what his intentions were," she said. It wasn't immediately clear if either suspect had an attorney.
Utah County Sheriff's Sgt. Spencer Cannon said that a few days after Schoeffler made the discovery, a tipster alerted authorities about comments on Facebook that mentioned the traps and the shelter. Detectives then tracked down the suspects, Cannon said.
He said it was fortunate that Schoeffler was the first to discover the traps, given his military training.
Schoeffler has served in the Army and is currently an Air Force reservist. He was last in Afghanistan in 2010 for his fourth deployment overseas.
"This James is a sharp kid," Cannon said.