BOISE, Idaho — Former Idaho Department of Correction officer Erik Thompson was sentenced on Wednesday to 97 months in prison for possession of a firearm connected to a drug trafficking crime. He will spend three years on supervised probation once he is released from prison.

Thompson is the fourth and final former IDOC officer to be sentenced for crimes connected to an FBI investigation into corruption at the prison south of Boise.

In February, 37-year-old Richard McCollough was sentenced to eight years and one month in prison after pleading guilty to two counts of possession of a firearm in furtherance of a drug trafficking crime. His 36-year-old co-defendant Timothy Landon was sentenced to three years and five months after pleading guilty to one count of conspiracy to aid and abet drug trafficking.

A fourth defendant - Robert Wallin - was sentenced to three years in prison for participating in the trafficking organization the men believed was moving large quantities of drugs into Idaho prisons.

The sting operation - in which FBI officers posed as drug dealers and recruited the guards - was launched after the Idaho correction department asked the FBI to investigate "concerns for corruption among IDOC correctional officers," according to the U.S. attorney's office.

No drugs or other contraband were brought into any IDOC facility as part of the sting operation.