Arizona's workplace safety agency is investigating the sexual assault of a female corrections officer by an inmate at the state prison in Yuma.

Agency spokeswoman Rachel Brockway confirmed the Arizona Division of Occupational Safety and Health is looking into the April 13 attack. She said Monday the agency can't provide more details about why it opened the investigation.

The probe comes as the Department of Corrections is appealing a $14,000 fine the agency levied on the department for failing to protect a prison teacher who was raped at another prison in January 2014.

In the April case, an inmate serving a life sentence for murder attacked the woman during a meeting in a housing unit office. Corrections spokesman Andrew Wilder declined to comment on the ADOSH investigation.