FORT COLLINS, Colo. (KXRM) – A Colorado jail inmate bit off his own thumb and then slid it under a door to a passing deputy early Wednesday morning, according to the sheriff’s office.

It happened around 2 a.m. Wednesday at the jail in Fort Collins. A deputy was conducting routine 15-minute checks in the high-security housing unit. As he approached a cell door, he saw something slide into his path from under the door. The deputy inspected it and realized it was a person’s thumb.

The deputy looked into the cell and saw the inmate bleeding from the hand. Medical staff determined the inmate had bitten his thumb off. He was taken to the hospital for treatment, but the thumb could not be reattached.

Deputies said the inmate had assaulted a corrections deputy in the past.

“This is an example of the growing number of inmates housed in county jails who suffer from apparent or diagnosed mental illness,” the sheriff’s office said in a statement. “While the Larimer County Jail does provide mental health services to inmates through diagnoses and medications, the jail is not the appropriate venue for treatment of mental illness.”