NORTH TEXAS (CBSDFW.COM) — A Texas man already in federal prison has been convicted of attacking a Bureau of Prisons employee.

A jury found William Lee Terrell guilty of assault of a federal officer resulting in bodily injury.

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Terrell was convicted in 2010 of bank robbery and ordered to serve a sentence of more than 19 years at the federal correctional institution in Big Spring — about 110 miles west of Abilene.

Terrell, who was on suicide watch, was placed under the observation of worker Krista Coccozza. The attack happened as Coccozza attempted to retrieve trash from a meal Terrell had just eaten.

According to evidence presented at trial, the 44-year-old inmate reached through the food slot in the door, grabbed Coccozza, and tried to get the keys to his cell off of a belt she was wearing.

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Additional guards came to Coccozza’s aid and were able to eventually free the keys from Terrell and secure his cell.

The prison worker’s injuries included a bruised lung, bruised ribs, sprained wrist, sprained elbow, sprained fingers and skin abrasions and she was unable to work for a period of time.

Terrell now faces up to 20 additional years in prison. His sentencing hearing has been set for April 29.

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