unless they took it to a professional lab there is no way they can tell what its genes are. if they are telling the truth however, that means you're friend might be able to have any criminal charges dismissed. if there were any "mint" genes in this substance its not cannabis. from what little I know about plants propagation and genetics, a mint plant cannot be crossed with a cannabis plant, their genetics are too different (unless of course you were to splice a cannabis plant onto a mint plant). most likely the pigs were talking out of there ass and were just trying to feel superior to your friend (bastards love to do that). if I were your friend, I would ask for a copy of the testing report that they have (unless they were lying).