I wonder why he didn't say he "forgot the password". Although it may seem implausible, how could they prove it's not true?
"TrueCrypt Boot Loader"
No expert is needed to prove that you are using TrueCrypt whole disk encryption. It has a huge stamp right up front.
tom@ubuntu:~$ gpg -v --list-packets flag.png.gpg
:symkey enc packet: version 4, cipher 3, s2k 3, hash 2
salt eae60ad4255dc4e2, count 65536 (96)
gpg: CAST5 encrypted data
OpenPGP encrypted data is easy to find too. It even tells you the algo used. The example is symmetrically encrypted, but it works the same with asymmetric keys. Even shows who it is encrypted for. Edit: formatting.tom@ubuntu:~$ gpg -v --list-packets file.gpg
:pubkey enc packet: version 3, algo 16, keyid 63E6E0BBB9FEE3A5
data: [2045 bits]
data: [2047 bits]
gpg: public key is B9FEE3A5
gpg: using subkey B9FEE3A5 instead of primary key 7A997B0AThen say I notify the cops about your 'illegal' activities.