TOPEKA, Kan. (AP) — Federal inspectors say they found no evidence the Topeka Zoo violated any standards before the death of a 35-year-old elephant.

Inspectors were called after the Dec. 11 death of Shannon, an African elephant.

Deputy Topeka city manager Doug Gerber says a veterinary medical officer from the U.S. Department of Agriculture presented a report to the zoo Tuesday.

The cause of the animal’s death has not been determined. The veterinary pathology department at Kansas State University is evaluating tissue samples taken from the elephant.

Shannon died that day after she spent about 20 hours on the ground over a two-day span. When she was found on the ground Dec. 10, a team lifted her back up but she was found back on the ground the next day.