How do I find a Yahoo member by their user name?

I own a yahoo group. One of the members thought he was moderated and sent me a threatening e-mail. How can I find out who he is? Is there anyway I can search his fake name or Yahoo e-mail to find out who he really is? Can I report or forward this threat...

How can i find my yahoo user name. I remember my password. I just forget my user name. Thanks for your help.

I use it these days to check profiles of people who message me on MySpace and MyYearbook who ask me to write them on the Yahoo mail. If I see a profile that's been there a while I'll write back, but if they just registered that day and there's no details...

i know his yahoo id from when he instant messaged me, and his first name but cant find his profile. how do i find his profile?

it was someone that i played against in yahoo pool but i forgot their user name

I got a IM from someone and they told me that they had a crush on me and that they were shy,And that they never been able to tell me for reasons which I would quickly identify as obvious if i knew who it was. And to visit there yahoo profile, User name...

sorry but english is not my native language.can someone give me list of yahoo user's name has "dth" (i can't remember fully her name) thank you very much.

Trying to find an email address for someone on Yahoo Auctions. I have the user name. Need to ask them a questions regarding contacting authorities. Thank you.