You can use kill to stop the process.
For a 'polite' stop to the process (prefer this for normal use), send SIGTSTPSIGTSTP:
kill -TSTP [pid] For a 'hard' stop, send SIGSTOPSIGSTOP:
kill -STOP [pid] Note that if the process you are trying to stop by PID is in your shell's job table, it may remain visible there, but terminated, until the process is fg'd again.
To resume execution of the process, sent SIGCONTSIGCONT:
kill -CONT [pid]