Why we have plainclothes cops

Boston Police report a plainclothes officer was standing on Dorchester Avenue in Fields Corner eating a piece of pizza last night when a guy came up to him and asked him if he wanted to buy some dope - and then pulled out a bag of beige powder:

The plain clothes officer at that time identified himself as a police officer and the suspect exclaimed, "I was just kidding, it's my thyroid medicine."

Saeed J. Muhammad, 51, of Dorchester, was then arrested on a charge of possession of heroin with intent to distribute.

Innocent, etc.