How can I find out if someone is hacking my Mac?

I have tried that many times. Nothing happens, they dont have time for that. I have changed my passwords many times as well. Does nothing on this log look strange?

There are also many other reasons why I think he can access my mac. He has referred to stuff I have been saying while chatting and using other forums.

Well - for a start - you should consider a new installation. Make a backup of all you data and start with the system boot CD. Take care that you got all drivers and passwords ready - then clean the system - this should keep him away.

Tolomir

Thank you but I know this.. my problem is that he has been harassing me for almost two years and it was only recently someone said that it sounded like he was using a program to spy on me. I am getting to the point of desperation and need to proof that he is doing all this shit to my private stuff. So hopefully I will find something that can link it back to him. But I dont know how! But thanks

I noticed that you have Adobe CS4. You should be aware that some, shall we say less than 100% legitimate, copies carry some sort of Trojan so it may be possible that there is a key-logger installed. I'd agree with the previous posting  about rebuilding from scratch.

Backup your personal data then reinstall the OS and all apps from original (I.E. Manufacturer) source material. If you've somehow squires disks or installers that you can't be 100% sure are genuine, don't use them this time.

What that person does is stalking and this is a crime - go ahead - call the police.

http://en.wikipedia.org/wiki/Stalking

Stalking is a term used to describe unwanted attention by individuals (and sometimes groups of people) to others. Stalking behaviors are related to harassment and intimidation. The word "stalking" is used, with some differing meanings, in psychology and psychiatry and also in some legal jurisdictions as a term for a criminal offence. It may also be used to refer to criminal offences or civil wrongs that include conduct which some people consider to be stalking, such as those described in law as "harassment" or similar terms.

I have reported it to the police. I was just on the phone with them again to find out wether they can help with localizing the IP address used to log on my facebook but they cant help, they suggested I reported it again, and then maybe with time they will look at it again. I have the rights to not have to worry about someone spying on me and using my accounts but there is nowhere to get help.  
Ok, so my last question: What should be my next step to try and find out about how he accesses my stuff? There must be some way to spot something??

You could try Little Snitch (http://www.obdev.at/products/littlesnitch/index.html)

It's a firewall for your Mac but it also tells you where data is going to and coming from. It's very good. Here's their own blurb....
" As soon as youre connected to the Internet, applications can potentially send whatever information they want to wherever they want.

Sometimes they do this for good reason, on your explicit request. But often they dont. Little Snitch allows you to intercept these unwanted connection attempts, and lets you decide how to proceed.

Little Snitch informs you whenever a program attempts to establish an outgoing Internet connection. You can then choose to allow or deny this connection, or define a rule how to handle similar, future connection attempts. This reliably prevents private data from being sent out without your knowledge. Little Snitch runs inconspicuously in the background and it can also detect network related activity of viruses, trojans and other malware. "

By the way I'm not affiliated with the makers of Little Snitch in any way.

Hope this helps.

hey, ok thanks for the tip of "little snitch" but how does it actually work? When I go to connection history it gives me 4 different IP adresses. Does this tell me anything? I use my laptop at home, my studio and sometimes at my boyfriends.

If you keep changing your password and he knows it each time then he has access to your computer. Facebook do not email you your password as far as I can remember so this password must be being typed. Unless you are making a note of it somewhere on your computer. If there is no note on the computer then he is using a keylogger.

Make a copy of your files and reinstall your operating system on your mac. It is really easy to do, make sure you choose a fresh installation.

Software keyloggers are the most popular but there are also hardware keyloggers and keyloggers you can insert in to the keyboards firmware More info here http://en.wikipedia.org/wiki/Keystroke_logging

This site also has some useful advice http://www.getsafeonline.org/

What is happening to you is indeed a crime so keep reporting it to the police, he is accessing files stored on your computer.

When you are using Little Snitch just deny any outgoing connections from applications you do not recognise.

Also go to System Settings>Sharing and make sure you are not sharing anything, especially screen sharing.

If you are in doubt about reinstalling, go to an apple store and they will look after you.

Hmm, it seems like little snitch is only in a demo mode.. but I guess it costs to have it longer? Only worked for a short time..

Built-in 3-hour trial.
Little Snitch 2 - 1 Seat $29.95

I know why I stick with windows there you get 30 days in contrast to 3 hours trial. This is competition...

hm, should read the complete page, sorry:

The demo runs for three hours, and it can be restarted as often as you like.       

http://www.obdev.at/products/littlesnitch/order.html

It didnt help me out but it was ggod answers. What I mean is that I still havent got a solution for my problem but I need to have my computer to be looked at by professionals. Thank you

You could take your machine in to an apple store and ask for advice. They are always very helpful and friendly in my experience.

Good luck, remember, if someone is accessing private files on your computer, it is very likely they are breaking the law and is a police matter.

Just watch out with those Apple stores - I've heard of two people in the last week that have lost significant  amounts of data after the Apple Store 'geniuses' supposedly 'fixed' their Macs.