You can always use a whois on the IPs, get the ISP and then send a letter to the abuse email of that ISP.. usually they have emails like [email protected] (usually shown in the whois) and show the IP and TIME in that email.. then the ISP should forward the email to that specific user (the ISP will know the email of that user that used that IP at that specific time)
But, I don't think it will be much of a success.
But, I don't think it will be much of a success.