Need help writing this trigger

OK here's what I want to do. A specific unit enters a region. Upon entering the region, a 60 second timer starts. At the end of the timer, if the unit that entered the region is still alive, a series of actions will fire that cause units to stop automatically spawning in that area. If the unit dies, the timer will be killed off, and units will continue to spawn as normal.

I cant seem to figure out a way to make a trigger that does that. I have it set up so far, where the unit enters the region, the timer begins, and at the end of the timer the units stop spawning. The problem is, I cant find a way to make it where if the unit dies, or moves away from the region the timer is killed and units keep spawning normally. Any ideas?

I was thinking I could do it with 3 triggers. First one would be something like "event- unit enters region, condition- unit equal to saidunit, actions: start timer, create timer window"
Second trigger would be "event- unit exits region, condition- unit equal to saidunit, actions: stop timer, destroy timer window"
Third trigger would say "event- timer expires, action- if saidunit is in region, than (actions here that stop units from spawning), else do nothing.

My problem is i dont know how to make a condition for the if/than/else statement that checks if the triggering unit is still in the region it entered. Need help guys! Thanks in advance.

-Huh

Boolean condition