At a midnight ghost-themed party, a rare necklace was stolen from a lockbox coated in invisible chemical indicator dye that turns bright blue upon contact with skin or clothing. Four guests wearing white sheet ghost costumes are searched under normal light: Guest A has yellow candle wax on his hem. Guest B has frayed edges on his eyeholes. Guest C has faint blue smudges around the interior armholes of his sheet. Guest D has grass stains on his knees. Who took the necklace?
Guest C.
The blue smudges around Guest C's armholes reveal contact with the chemical indicator dye on the stolen necklace's lockbox.
About this riddle
Detective riddles are tiny mysteries. Look for the detail in the story that does not fit; it is usually the clue that solves the case.
Difficulty: Medium. More like this: Detective riddles with answers or try Truth & Lie Island for a different kind of puzzle.
More detective riddles
A jewel thief claimed he spent the entire night of the heist asleep in a remote cabin with no electricity, reading a thriller novel by the light of a single tallow candle. Detective Cross arrested him upon hearing this alibi. Why?
Detective Ray walked into a freezing cabin during a blizzard. The sole occupant sat dead at a wooden table with a fountain pen in hand and a suicide note half-written. The ink on the paper was completely frozen solid halfway through a sentence, yet the cabin's iron stove was roaring with hot fire. Ray arrested the nephew visiting outside. Why?
Detective Miller stared at the freezing winter crime scene inside the locked walk-in freezer. The victim was seated at a table with a half-melted ice cream cone resting beside his hand. Miller immediately arrested the store manager, knowing the ice cream proved the victim had not been locked inside overnight as the manager claimed. Why did the ice cream give the manager away?
A hiker was found dead in the snowy woods with footprints leading up to his body, but zero footprints leading away. The snow had stopped falling hours before his death. How did the killer leave without footprints?
Inspector Lane investigated a warehouse robbery. The burglar stole heavy gold bars, carrying them out through a narrow window too small for a normal person to pass through while holding heavy items. The window had no ropes or pulleys attached. How did the thief get the gold out?
Inspector Reyes is checking the order in which five suspects left the locked library. Kira left before Carmen. Boris left before Iris. Pavel left before Kira. Carmen left before Boris. Who left last?