THOMASTON, Maine — Police have figured out one way drugs are getting into the Maine State Prison.

On Monday, police and a prison staffer reportedly found $30,000 worth of heroin inside the Maine State Prison Showroom bathroom apparently waiting to be smuggled into the prison.

A woman dropped off the drugs at the Showroom — a store in downtown Thomaston that sells goods such as wooden toys and furniture made by inmates. The store employs prisoners who are allowed into work-release programs. One of those inmates planned to take the drugs into the prison, Tim Carroll, chief deputy at the Knox County Sheriff’s Office, said Tuesday.

Criminal charges are pending against the woman, who has not been arrested and whose name has not been released.

When prisoners get back from their work release programs, they are searched for contraband, according to Jody Breton, associate commissioner of the Department of Corrections.

“Contraband is always something we have to watch for,” Breton said. “[Showroom work release] is an important program at the prison, we just have to be vigilant about contraband.”

The sheriff’s office was helped by Investigator John Scheid of the Maine State Prison, Maine State Police and the Thomaston Police Department.