if the documents are complete, number plates are original try & negotiate at reasonable price buy it.
It is just stupid market and the criminal dealers who create non-sense hoax.
Request the owner to obtain an NOC from the police station or ACLC if they registered and FIR for car theft. Normally in such cases there is no FIR but a plain report which is only to ensure that in case of any crime in car the owner is safe. if car is not recovered in 21 days an FIR is registered Then a clearance letter is needed from police station that car is not involved in any case and clear for sale by owner.