I have this process running:
342 pts/2 T 0:00 sh -c sudo screen /usr/bin/python /usr/bin/btdownloadcurses \"http://zoink.it/torrent/732A4A9B54B7E3A916C2835
If you have that zombie process open in a terminal, you can Ctrl+z it, which on most shells lets the process run in the background and outputs something like:
Ctrl+z
[1] + 69880 suspended someprocess
You can then actually kill it with:
kill -9 69880
the same id that was shown when suspended.