TrueCrypt
From Forensics Wiki
TrueCrypt is a Windows program to create and mount virtual encrypted disks.
Forensic Acquisition
If you encounter a system that has a mounted TrueCrypt drive, it is imperative that you capture the contents of the encrypted drive before shutting down the system. Once the system is shutdown, the contents will be inaccessible with an encryption key generated by a user's password and/or an additional datafile.
