(edited, to make it easier, on 18 March, 2008… thanks Adam/anon for suggesting a simpler story)
There are two twins. One of them ALWAYS tells a lie. While the other could tell the truth or tell a lie.
One of them, whose name is Santosh (he’s the guy who ALWAYS lies), commits a murder.
The twins stand before the judge, knowing that Santosh committed the murder, asks the first fellow, “Are you Santosh?”
The guy says, “Yes I am.”
With this information, the judge was able to figure out which of the two was the murderer.
Can you?

hey hey hey i’ve been spending a few hours on this riddle. . .
but i cant seem to figure it out. . so pease if you can send the answer to my email or post it plz. !!1
To adsad:
Sorry about this, adsad, but this is a riddle I heard many years ago and I remember it had a solution. However, when I recovered my old files, all I had was the riddle, and no solution. So I put it up here, partly to open this question to the “world wide web” so that others can maybe find the solution.
I must admit that I too spent a long long time trying to figure it out… but couldn’t.
All I can say is that the question IS authentic. And I do remember it had a solution. But I’ve forgotten it.
Perhaps… for all time!
the one who always lies has to lie when asked….”Are You Sanotsh” the only possible lie is “No” if he is Santosh…so the second twin is santosh
Santosh always has to lie no matter what. SO if he is asked are you santosh, he will say no i am not.
The other guy lied, cos he can decide to tell the truth or lie, or whatever he wants