For decades, the federal government has been working to restore wolves to the Northern Rockies. While the population has expanded to more than 1,700 in several states north of Colorado, many biologists and wolf watchers believe it will only be a matter of time before they’re re-established here (if they aren’t already) after being wiped out in the last century. That’s why the death of a female gray wolf near Rio Blanco back in 2009 is making headlines this week. The wolf, wandering about 1,000 miles from the Yellowstone National Park area, was poisoned, according to the Grand Junction Sentinel. The substance used in the poisoning, Compound 1080, is illegal in Colorado but allowed in some states for collars worn by sheep and goats as protection against coyotes.

Now, officials are attempting to locate the human source responsible for the wolf’s death, writes The Associated Press, quoting Steve Oberholtzer, a special agent in charge for the U.S. Fish and Wildlife Service: “That’s what we’re hoping to find: who has it, and who’s still using it.” Wendy Keefover-Ring of the group WildEarth Guardians says the poison should not be used at all because it represents a threat to many wild animals. In 2009, the Environmental Protection Agency turned down a request from the group and others urging a ban on Compound 1080, as well as spring-loaded sodium cyanide devices, used to protect livestock.