W32.Spybot.Worm can't find out where it came from....

     I have been trying to determine where it came from. This worm has been detected on my system two times. The detection dates were;

                                10/16/2009, 10/16/2009 <list it twice for some reason>, 10/9/2009, 10/8/2009. 

 

I'd like to be able to find out where this came from. But there aren't enough details in "more details" option. I may know who did this, but I would like to be able to verify before I pursue any legal action or simply contacting their isp. I can't even find out which directory it was found it...which I find odd. I find it peculiar that I can't get any of this information because, usually, even the ip of an attacker is shown. Does the fact this isn't the case mean it is from a file which was downloaded?

 

 Thanks in advance for your help.