Thief Dead in unknown location

While running 15, my thief (GrunkleStan) hit a tp box and died in the subsequent encounter. When I searched for him while on 15, I got a message that he was below me.  I went to 15U and searched again.  When I did that, I got the message that he was not on that lvl.  So, he is below 15, but not on 15U after hitting a TP box on lvl 15.  Need Help!  Any suggestions, or DM want to help me out?

Other interesting note: I do get the option to press 'r' for a rescue, but when I press 'r' I don't get anything.

Thanks,
will