From the Phoenix New Times:

On the night of May 21, the first calf was killed. The next night, investigators said, the culprit struck again — another dead calf, less than a mile away from the first. A week later, another calf carcass was found.

By now, wildlife managers had a prime suspect: a lone female Mexican gray wolf with a failing radio collar. To them, the wolf was known as F1557.

Click here for the full story.