KANSAS CITY, Mo. (AP) – A former Missouri paramedic who gave patients sterile water in place of their painkillers has been sentenced to 2.5 years in federal prison.

Federal prosecutors announced Friday that 31-year-old Joseph Comstock was sentenced Friday for three counts of tampering with a consumer product.

Comstock worked for two ambulances services in Bethany and Gallatin, Missouri.

Officials with the NTA Ambulance District in Bethany discovered in 2015 that someone had tampered with morphine syringes and other drugs.

Investigators found similar problems at the Gallatin ambulance service when Comstock worked there and conducted surveillance, which uncovered Comstock going into cabinets containing drugs.

Comstock admitted that he began tampering with drugs in 2014 after having his tonsils removed.