Sabotaged Computer Help

[Lyrima]

My brother's son might have sabotaged my brother's computer at the request of his son's mother.  My brother is mired in a nasty divorce with this woman.

To avoid the details, his computer was used w/o his permission or knowledge at least twice.  His admin password was removed twice.

He is concerned that spy software has been downloaded onto his computer or that a computer has remote access to his h/d now.  He is also concerned that there is now some way to track his keystrokes....

We aren't sure what is possible when someone who wants information from your hard drive from another computer can do and how to stop them from doing it.

First we want to know how to sweep for anything on his computer and

Second we want to know if there is some way to track where the information is being sent and

Third we want to know how to GET RID of whatever is found.

TY TY TY !!

Your speedy reply is appreciated.