Cannot access MacBook AIr. Password unknown. Probably no recovery partition.

A friend gave me his son's MacBookAir. His son is deployed and not available. The password is unknown. Using option and Cmd-R at startup doesn't help. Can't reinstall an OS. Used a USB stick of OS 10.9 to boot, ad a recovery partition not present and Terminal could not resent the password. Could not UNLOCK the drive to do a reinstall.,

What to do to access and reinstall OS ?