AUGUSTA, Maine (AP) — A worker at a Maine psychiatric hospital is suing a former patient who was later sentenced to prison for assaulting her.

The Kennebec Journal reports that Sally Nichols, an employee of Riverview Psychiatric Center in Augusta, is suing former patient Arlene Edson. Edson pleaded guilty to four assault charges last year and is in prison in Windham.

Nichols alleges that Edson punched her in the head from behind, causing serious injuries.

A judge has approved a $100,000 attachment on Edson's property as Nichols' suit moves forward.

In a separate case, Edson received $180,000 in a settlement with the state after claiming that she was pepper-sprayed during her time at the hospital.

Edson was previously convicted of assaulting another hospital employee.

Edson's attorney did not respond to a request for comment.