WISCASSET, Maine (AP) The Maine Drug Enforcement Agency says six people have been charged with smuggling the drugs Suboxone and LSD into the Two Bridges Regional Jail in Wiscasset.

Officials said Tuesday that the investigation began in January when an inmate instructed two people to hide the drugs inside an envelope marked as “legal correspondence.”

Both drugs are easily concealed and the envelopes had a return address of a Maine law firm in an attempt to keep jail authorities from opening the letters.

Mid-Coast District Task Force, investigators at the Two Bridges Regional Jail, Sagadahoc County Sheriff’s Department and Topsham police participated in the investigation. The six who were arrested include five adults and a juvenile.