[stunnel-users] How do I kill stunnel?

I've got an application that starts stunnel using equivalent of a fork/exec. The stunnel process then appears to fork off multiple copies of itself.

Before the application exits, it needs to stop stunnel. I send a SIGINT to the PID that was created using the fork, but only the first "master" copy terminates -- the master stunnel process doesn't terminate its children when it exits. So I end up with a bunch of "orphaned" stunnel processes. They're not zombies, they're process that are either in state R or S (runnable or sleeping).

How do I tell stunnel to not only terminate, but to terminate whatever child processes it has created?