In fact, if you have the pid of the process that you want to kill, you can kill it with Win32::Process::KillProcess($pid, $exitcode), irrespcective of how the process was started.
True, but finding the pid for a process is a right pita! Every time I want to do it (about 11 months apart on average) it seems to take an hour of trawling through MSDN to find what needs to be done. Then after 10 months I forget how to do it.