hi all sound daft but want to know???

has anyone ever bought a rs ford and it turns out stolen
the reson why i ask is i new of a guy who bought an rs and didnt have a v5 for it has mots and hpi cheaks done in the past and he was saying a week or so ago that hes still not had a v5 come though even thoug the sellor says he sent it?
i think its dodgy and is stolen
my question being is whwere or how do you find out and if it is stolen or what ever then will he lose this car???
any help or addvise pls
thanks ian