Re the "Paul is dead" conspiracy: Couldn't known fingerprints from the orig. paul be compared to the impostor?

Ive been reading a bit about the Beatles "Paul is dead" cover up and it seems to me there were a number of tests which could have been performed to prove that Paul McCartney was (and is) in fact Paul McCartney and not an impostor (Billy Shears) put in place after the real Paul M's death, as some may argue.