The victim was found in a sealed fallout shelter with zero oxygen remaining. The only entrance was a heavy steel door locked from the inside. There were no tunnels or vents. How did the killer pull off the crime?
The killer pumped out the oxygen
By extracting the oxygen via an external vacuum or valve system, the killer didn't need to enter the shelter to cause asphyxiation.
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: Hard. More like this: Detective riddles with answers or try Truth & Lie Island for a different kind of puzzle.
More detective riddles
Three kids race to build the tallest squirrel tower. Omar finished before Noah. Noah finished before Max. Who finished last?
A wealthy art collector was murdered during a blackout. His priceless painting was replaced with a cheap modern replica. The prime suspects are the three people who visited him that evening: the electrician, the art dealer, and the blind poet. Who is the thief?
Detective Reed entered the freezing cabin where a smuggler sat wrapped in three woolen blankets. The smuggler insisted he had been shivering alone since midnight. Reed noticed the candle on the table had melted wax pooled evenly on all sides, despite a fierce gale blowing through the broken window. Why did Reed arrest the smuggler?
A jewelry merchant was found bound and gagged in his shop. He claimed three masked men tied him up at noon and looted the safe. Detective Cole examined the crime scene and noticed a candle burning on the front counter. The candle was 6 inches tall and burned at a rate of 1 inch per hour. By the time police arrived at 2 PM, the candle was completely gone. Cole arrested the merchant for insurance fraud. Why?
An old sea captain was found murdered in his seaside cottage. The front door was locked from the inside, but the back sliding glass door was wide open to the salty ocean breeze. A heavy brass anchor sat on the living room floor, covered in fresh lake water. The detective smirked at the rookie cop. What detail exposed the staged crime scene?
An antique pocket watch was reported stolen from a locked study. The owner insisted the room was sealed from the inside and nobody could have entered. Detective Reed walked in, looked at the grandfather clock ticking in the corner, and found the watch hidden inside the pendulum housing. 'It was an inside job,' Reed declared, 'done by someone who never even set foot in this room.' How was that possible?