Like Goblin King said. Found in the Combat/Defending section at the top of p.11 of the British EU Rules of Play:
Eliminated characters and monsters are immediately removed from play. Any
Equipment or gold the eliminated character had may be picked up by another
character, who searches for treasure in the room or passage in which the
character was eliminated. However, the evil wizard player may also claim the
Equipment or gold if, on his next turn he moves a monster into the same room
or passage, in which the character was eliminated.
If a monster picks up the possessions of the eliminated character they are removed
from the game, the monster may not use either the Equipment or the gold.
The attacker may now move if he has not already done so. Play then continues
with the player on his left.
The italics used for
next aren't mine, but are in the Rules of Play to emphasize the evil wizard player must wait a whole turn to claim possessions. This gives the Heroes that much time, 1 round of turns, to claim the dead Hero's possessions first.
As a side note, I wonder if the condition that the evil wizard must move a monster into the same room or passage to claim the Equipment or gold is mistated. If it read "...he moves a monster in or into the same room or passage...", then a lone monster wouldn't need to leave and then return to claim the Equipment or gold. This would more closely resemble the NA rules. This leaving requirement is thematically strange to me. I guess if the intervening time was thought of in reverse, where the monster first loots the Hero and then leaves the room or passage, then it could work.
There is also a potential problem game mechanics-wise. If a lone monster moves before it kills a Hero, it must spend its next turn leaving the room or passage before it can move back into it to claim the possessions. In large rooms or long passages it isn't always possible for slower monsters to make it back in time for the evil player's next turn, thus it sometimes can't claim the treasure using the rules as written. I feel requiring a slow Zombie 2 turns to loot and escape with a dead Hero's possessions would work fine, however, so I'd suggest this fix: "...The evil wizard may also claim the Equipment or gold if, on a
following turn he moves a monster into the same room or passage, in which the character was eliminated...."
I prefer the second rules fix to the first one I suggested, as it better represents slower monsters making off with Equipment or gold at a slower pace. The awkward exiting and re-entering is primarily there as a mechanical timer (usually), so it can be thought of as the monster needing that much time to loot and then move out of sight. If a situation arose where an exiting monster was then in line of sight of a ranged attack, I'd allow the attack as a kind of parting shot to perhaps down the looting monster before it escaped.