How does a person know if their account has been hacked?

Friend gets messages from hacked person?

• let me explain the situation, I am person A, my friend is person B, the hacker is person C, and the behacked (person who got hacked) is person D so person B get's messages from Person D, sexual messages to be exactly, and I know that person D's account is hacked, because I personally know person D, I am 99% sure it's peson C who did it, but I want to prove it, I was thinking about matching IP's but I have no idea how to do it, any suggestions?

• Answer:

  What account was it? If it's facebook, tell person D to report it here: Account got hacked: http://www.facebook.com/help/hacked Reporting a violation: http://www.facebook.com/help/?page=204546626249212 See if facebook could tell person D the IP address of the person who hacked or accessed his account for the past few days in question. You can try getting an email from person C or ask person B to check the emails he received from person C. The email has a header containing the sender's IP address. So as they say "If the shoe fits" then there you go, you've nailed person C.