Reformatting and repartitioning a hard drive will NOT erase your data. Encryption is NOT enough Your deleted E-Mail can still be read. Passwords can be written to the swap file .TMP files contain your sensitive data. Formatting disks does not remove data. Defragging does not remove deleted data.
Sensitive data is written to the end of files.
The use of an untrained person could cause the inadvertent destruction of data, overlook deleted, hidden or encrypted data and could cause inadvertent writes back to and alter the original media. Even if the untrained person found relevant data, the data will probably not be legally admissible or unusable. This is because of the untrained person's lack of forensic training and credentials, that the methods used were not forensically sound, and their lack of understanding of the technical issues involved. It is also relatively simple to hide files that normal. The hidden file simply will not be displayed, and its contents will not be found or examined.