Here's an article about how science has discovered a process in neurology in which long term memories are accessed/preserved... essentially disrupt the molecular machine and you erase a person's longterm memory temporarily.

I hesitate to think how this could be used... for evil...

http://pressesc.com/news/1088/16082007/memories-can-be-erased-scientists-find

however... Babylon 5 did an episode in which there was a process called mindwiping in which a serial killer type person was no longer executed but their memories were simply wiped and they were reprogrammed and subjected to a life of community service unaware they'd ever committed the crimes they did...

Really made one think about the implications of one's actions in given conditions... etc...

--Ray