SIOUX FALLS, S.D. (KELO) — The South Dakota Department of Corrections has released the cause of death of a 42-year-old inmate, who died on March 31st at the Sioux Falls Community Work Center.  According to a DOC spokesperson Collin Daugherty died of hypertensive heart disease. His toxicology report did not indicate that any illicit drugs contributed to his death.

According to the South Dakota Attorney General’s Office, at the time Daugherty died, two other people in the work release area experienced overdose symptoms but did not need to be hospitalized. According to one statement made by an inmate, the substance in question was K2 or synthetic marijuana.

KELOLAND News has asked both the Attorney General and Department of Corrections about the investigation into that incident, which according to our sources resulted in a lockdown. We’re told that the DOC Special Investigations Unit and DCI are conducting an ongoing investigation.

Daugherty was serving time for burglary, grand theft, and identity theft out of Lawrence County.