PID of a bash process not captured by $!

While this part of the script works fine: geany & pid=$! ... kill -KILL $pid This, instead, does not. lxterminal & pid=$! ... kill -KILL $pid Looks like a bash process remains in the background, but it is not identified by $pid. How can I get the PID of the terminal window, such that the process can be killed afterwards? Note: I also tried to kill it by its name, but the --title option provokes some kind of conflict with PROMPT_COMMAND.