All of Facebook's customer service is handled online, through the Help link at the bottom right of every Facebook page. Select the help topic relevant to your problem, then click the "Send us a message" link at the bottom of that help topic page. This will flag your issue specifically to your problem.
Phone: 650-543-4800
How to reach a live person: Facebook does not currently offer telephone support. You can press 0 to leave a message, but not sure what that does.
EDIT: Facebook will not assist you with log files or other investigationinvestigational information unless you provide a copy of a police report relating to the incident, or a court subpoena.