A Monroe County Sheriff's deputy was sent to the hospital after finding an unknown substance in an inmate's mail.

A Monroe County Sheriff's deputy was sent to the hospital after finding an unknown substance in an inmate's mail.

According to the Monroe County Sheriff's Office, a jail deputy working inside the jail on Plymouth Avenue was checking an inmate's legal mail around 11:30 a.m. on Saturday. While checking the mail with the inmate, the deputy found an unknown substance in an envelope.

The deputy had a negative reaction to the substance and was transported to Strong Memorial Hospital. The deputy was treated and released.

The substance is currently being analyzed and tested at the Monroe County Crime Lab.

The sheriff's office is conducting an internal investigation involving jail command staff as well as Criminal Investigative Services.

This is a developing story. Messenger Post news partner News10NBC will provide more information as it becomes available.