It reads in the rules as:
The overlord receives one threat per hero per turn, in addition
to gaining his usual one threat for every two surges he spends
when making attacks.
Can I assume from this, that when a hero is killed and removed from the encounter, the OL gets one threat less every remaining turn of the encounter? Also, in a normal dungeon, when a hero gets killed, or goes to Town to heal, does it affect the Threat the OL receives?