Remove all evidence from computer
Files on a windows computer are logged by fragments, im not going to go into the dis-benefits of NTFS especially for being the default for all windows operating systems. NTFS however leaves traces of all files, and keep them on fragments, the only program thats available publicly (thats not meant for this purpose btw) is Recuva, which scans a drive for files in fragments, then deletes them... Recuva also has the option to Securely overwrite files at a NSA level (7 Overpasses) or guttmann (35 secure overpasses), enabling a deep scan searching for "all" content may take awhile but if you need evidence removed this is the way, it may also be recomended to run a disk defragment (comes default with windows) to eliminate empty fragments left over by recuva...
(linux btw leaves no fragments, so this is unnecessary on a linuz computer)