Doh you weren't supposed to read my post yet - I wanted to edit it to say I was wrong, everything's right as far as I know, yadda yadda ...
It turns out there was a misunderstanding of what happened. Jackaro did guide the deemer, but he forgot where he was and killed himself (he was one of the two that died and I didn't realize that - turns out he *had* guided it halfway across the map, but he had also guided it *back*). Part of the miscommunication was that Jackaro did not know that you could deemerder as part of a deemercide.
We have had a few more deemerders, but they've all been due to deemercides.
So, as far as I know, you can't kill someone with a deemer without killing yourself in the process.
NOTE: If you can provide information to the contrary, as Dru indicates above, he'd be very interested in knowing the details.