The next time someone knocks at your door, you may want to think twice before opening it.

The Marathon County Sheriff's Dept. is receiving complaints of a scammer salesman who's getting very creative.

Allegedly a man has been going around door-to-door claiming to sell books, but this person has an ulterior motive and a plan to get his hands on your prescription drugs.

According to complaints, the man is dressed appropriately and well-spoken. He gives a ales pitch to sell encyclopedias and then asks to use the bathroom.

Once inside, he goes straight for the medicine cabinet, emptying all prescription medications.

A lieutenant says the crime is new to the area, but isn't surprised an alleged drug addict would get creative to get his fix.

"They will even have products they claim to sell. They may even have a shirt with their name on it, that doesn't mean they are actually who they represent to be," Lt. Dale Wisnewski said.

He recommends never allowing a salesperson into your home, or anyone else for that matter.

And if you're not sure a salesperson is legitimate, you can ask for his or her solicitor's permit...something that's legally necessary to sell door-to-door in any area.

"If they're not from the area, people selling meat door-to-door they would need that. People selling books, as the allegation thi sis, those people would be required to contact that local jurisdiction," Lt. Wisnewski said.

If they can't show any documentation, you can call your local town chairman, village president or mayor's office to find out if that person is on the list.

If not you should call law enforcement, because what they're doing is illegal.

"Do not let them in your home. There is not a reason why a salesperson would have to get in your house," he said.

But not every solicitor needs a permit. One exception would be girl scouts selling cookies.