yes and no. there are programs out there that a few key strokes you can erase all sensitive areas on your computer. it is for people who in case of a raid they can run to the computer and press the keys and it gets rid of the info yo0u set up the program to erase. weather it is a few files or the whole hard drive.
now the no part. the feds and computer geeks can get into the computer and dig up stuff that is deleted. it leaves a trail on the harddrive. even though you deleted it, it still has a trace and can be found. the computer hacker people are geniuses. all they do all day long is find out different ways to hack a computer for info.