statistics devices??

hi all
im new to this forum lark and was hoping you could help me with a little problem i have. I need to find the ip for someone who joined my forum today. now the problem i have is one of the admin team deleted their membership before i had chance to ban or make note of the ip address.
I have read here that it is possible for me to still get this info with a little work (it would be worth it as i want to aviod future problems with this person) by installing statistics devices.
could someone please point me in the direction of how / where i can get this.
any help would be much appreciated!!

I dont mean to be impatient but is there anyone that can help me??

well it depends on how many people you have banned and how many guests you have had post on your forum, IF he/she is the only one that has been banned and you havent had any guests post, then just look for a post made by "guest"(which will be this person) and get the IP from there....that is the only way i can think of getting the IP number

other then that i dont know of any "statistic devices" you can use to be honest

thankyou for trying to help. this person did not post on the forum so that is not an option im afraid