The chest is indeed locked. Seeing as how you searched the bodies above (which I missed), on the neck of the bugbear that was carrying the axe, you find a thong around its neck with two keys.
Looks like you find a little stash. In the chest is a suit of leather armor, a shortsword, a bow, a quiver almost filled with arrows, a sack, and a backpack.
** It's the middle of Day 4. I don't think you're getting back in time.
"Ok - here's what we got... Cugel - as we're both arrow-users - let's split the arrows...
The bow, shortsword and leather armor are up for anyone that wants them..."
(Si'Nat takes the sack and dumps it on the bed... electrum, silver and gold pieces fall onto the bed.)
"Everyone will get their equal share of these..."
(Si''Nat then takes the backpack and places its contents on the table... The backpack rope, two flasks of oil, and a set of thieves' lock-picking tools and sit on the table...)
Kurik says, "I don't need any of that stuff, but how about we just divvy up the treasure afterwards? No sense in wasting time now to count it and divide it equally (or we can do it when we camp for the night)."
You exit the room and go west for 30', turn south for 10', and come to an intersection. The passage continues south for 10' before ending in a door. It also goes west for 20' before ending in a door.
"South or West... well 's' comes before 'w' in someone's language - so we'll check the South door first..."
(Goes up to the door and listens for anything inside - if nothing heard will attempt to open - checking keys if needed... If Cugel would like to check for traps, that is fine... Preps for battle with bow and sleep...)
Cugel doesn't find any. Si'Nat tries opening the door and finds it locked. He tries his keys and finds the other one he took from the bugbear fits and unlocks it.
"The name's Cullen. I've been held here for about three weeks by these goblinoids, and since I haven't seen a dwarf or elf working with them, I assume you're fighting against them. Is that correct?"