Disabling a keylogger that was put on my MacBook (without my permission)

Hi, guys. Normally, my Google-fu is pretty strong for my computer problems, but this one is over my head.

A little background on my problem without (hopefully) getting too personal: My former roommate turned into a stalker, and one of the things he did was put a keylogger onto my MacBook. This emailed every single thing I typed to him. When all of this came to light, the police had my laptop for a few days. They couldn't figure out how to remove the keylogger completely, but they did track down the name of the program. (I believe it was "Keylogger Pro for Mac".) They said that if I pressed "control"+"option"+"command"+"J" whenever I turned on my computer, it would disable said program, which I've been doing. (Former roommate has been in jail this entire time, and I doubt he's had access to email, anyway.)

Tonight I was clearing out some old files in my Download folder, and when I went to empty my Trash, one image file wouldn't empty because it said it was in use. Of course, I hadn't opened it, and it was a picture of me the former roommate had taken. I opened the properties and tried to disable it manually, but (obviously) to no avail. I'm pretty sure that's where the ugliness has been hiding.

If anybody can help me out -- you'll have no idea how much of a weight will be lifted off my shoulders.

Thank you so very much in advance.

This is a very good reason not to have your User Account set to Admin.

To force empty the Trash hold Option down and choose Empty Trash.
Can't empty trash.. item still in use

The Option+Empty didn't work, but the commands into Terminal did. Thanks for the link.

As for putting the keylogger on my computer, he did it right under my nose with some pictures from a night out. Like, I was sitting right there, so at the time he didn't need to circumvent any passwords. Then again, the whole keylogger thing turned out to be the least of what he did.

He was my roommate because I believed we were friends. Of course, had I known how much of a psychopath he was, I never would have roomed with him in the first place. I don't even know why I'm telling you this -- I guess I just don't want to look like an idiot to some random stranger on the internet.

Anyway, thank you all the same. You've just made my 2012 even though it's still a few hours away for me. I'll probably still be running the disable procedures every time I boot up just in case.

If you find out the exact name of the key logger app then you can try downloading it and seeing if there is an uninstaller that comes with the installer. Some apps are a pain to uninstall if you've thrown out the installer file. I always look to see if there is an uninstaller icon before un-mounting the disc after any app install I do.. and yep, make your account a Standard one straight away!

I have Little Snitch installed which asks for permission when a process or app tries to contact the internet. It's difficult initially to know what to allow and what to deny but you soon get the hang of it and at the end of the day there aren't many security threats for the average Mac user even with Little Snitch installed.

Activity Monitor (Applications ~> Utilities) is another place to look for unusual processes that might point towards an installed Key Logger ... just google if you are unsure of any names. Believe me, there are some really weird legit names to be found running behind the scenes ...