Conservationists said wildlife managers' decision simply reinforces a double standard when it comes to killing endangered wildlife: All hunters have to do is claim they thought they were aiming at something legal to kill.
"It's wrong on several levels," said Michael Robinson of the Center for Biological Diversity. "It's part of a broader policy that sends the wrong message."
The gray wolf remains a protected species under the U.S. Endangered Species Act outside the three-state Northern Rockies recovery zone of Idaho, Montana and Wyoming. Federal law provides criminal penalties for those who "knowingly" kill protected animals. But unknowingly is another matter.
The dead wolf turned out to be the one spotted wandering on the Grand Canyon's north rim and later dubbed "Echo" by a 10-year-old boy from Oregon in a naming contest.
Known to researchers as 914F, Echo had been fitted with a radio collar on Jan. 8, 2014, near Cody, Wyo. The female subsequently covered hundreds of miles across three other states, attesting to the predator's ability to return to its historic range. It weighed 89 pounds when it was killed.
While wolves are known to pass through Utah, no pack has been established here since the predator was exterminated decades ago.
Through a Freedom of Information Act request, Robinson obtained 150 heavily redacted pages from Fish and Wildlife's investigation files. Documents indicate two central Utah men were out before dawn on Sunday, Dec. 28, 2014, stalking cougars.
While driving down a Forest Service road in the Birch Creek area of Fishlake National Forest at 9 a.m., they saw a cow they thought was limping. They stopped the truck and hopped out, one of the men holding a .223-caliber hunting rifle with a 10-power scope. As they approached the cow, they saw what they thought was a coyote in the sagebrush and quickly decided to kill it.
"We seen a coyote," one of the men wrote in a statement included in the report. "I jumped out of the truck as the coyote went behind a sagebrush. I had a shot and took it. The coyote just dropped."
The bullet went through the canid's chest cavity, but didn't kill it. When the men walked about 120 yards to their catch, they realized it was still alive and the man pulled out another weapon, this time a .22-caliber pistol.
"I shot two bullets in the head to make sure it was dead," he wrote.
The pair then realized that the animal lying at their feet was a wolf.
The men made eight calls, including to a high school acquaintance who happened to be a state conservation officer. When they couldn't reach him, they drove to his home to report the kill.
The officer drove to the scene of the shooting with a second officer, then notified federal wildlife officials of the wolf's death.
A necropsy yielded mammal hair in the dead wolf's stomach. It belonged to elk and deer, not livestock, Robinson said.
"Both [men] appeared to understand the gravity of their mistake and showed remorse," the state officer wrote in his report. "It appeared that the [men] made an honest mistake and turned themselves in so they could make things right."
Federal prosecutors are given leeway in determining whether to charge hunters who kill endangered animals.
"In accordance with current policies, the government may exercise prosecutorial discretion in circumstances where a bona-fide misidentification of a protected species occurred during the course of an otherwise lawful activity," FWS said in its statement.
Essentially, that case of mistaken identity gives the Utah hunter a pass, Robinson said. Others who mistakenly shoot a mule deer could have their license or rifle taken under state law.
"There should be a common standard for using a firearm," Robinson said. "There shouldn't be this exception."
Robinson said U.S. Attorney General Loretta Lynch could change the policy for federal prosecutors "with the stroke of her pen."
The killing also raised questions about the wisdom of Utah's coyote bounty program. Conservationists worry the $50-per-coyote-ear that Utah offers creates a financial incentive to shoot first and look second, and gives wolf killers an easy out.
Robinson said managers of the state's bounty program have taken no steps to ensure coyotes are the only animals killed.
Others argue Utah's free-fire policy for coyotes could ensure wolves never get re-established in the state because everyone who shoots one will claim they thought it was a coyote.
Utah Division of Wildlife Resources (DWR) managers, however, have taken notice of such criticism and vow to instruct bounty hunters on how to distinguish a coyote from a wolf.
The man who shot Echo had not registered for or participated in the coyote bounty program, according to earlier statements from DWR.
Fish and Wildlife's investigation report states that one of the men reported shooting "three or four" coyotes last year, but it's unclear whether he turned them in for a bounty.