Authorities are trying to identify "a large feline" that was spotted more than a week ago in Meacham Grove Forest Preserve near Bloomingdale.
Bloomingdale police on Friday issued a statement about the sighting, which was reported just north of Lake Street on the border of Bloomingdale and Roselle.
Chief Frank Giammarese said officers investigating a missing person case "observed what appeared to be a large feline" in a densely wooded area in Meacham Grove.
Giammarese said police are working with the DuPage County Forest Preserve Distict to investigate. The Illinois Department of Natural Resources also has been notified.
Deputy Chief Bruce Beck said the sighting was reported more than a week ago. He said officials released the statement to make residents aware "there's something out there."
"We don't know what it is," Beck said. "We can't say it's a cougar. We can't say it's anything."
Whatever the animal is, forest preserve officials have tried looking for it several times since the district was notified on May 23.
"We have not seen anything," said Sue Olafson, forest preserve spokeswoman, adding that no paw prints have been found either.
Giammarese said most wild animals tend to avoid human contact and encounters are rare. Still, he offered some advice for residents.
"As a precautionary measure until the animal can be positively identified," Giammarese said, "we are asking the public to be aware of their surroundings."