One day, in the interstellar space near the system "Calibri"...

The battleship B15, controlled from the control ship and flagship "Wielder", has just destroyed an opposing control ship with a long-range shot from a range of 1 light-second, killing all its crew. The crew of the Wielder rejoiced in delight. Now there are only 3 control ships left to destroy, and for them, victory is near.


"The captain's dead! The captain's dead!",

shouts someone from the bridge into a microphone, which catches it and spreads it all over the ship.

The delight of the surprised crew turns into panic, as the alarm sounds loudly. The guards rush to the bridge. They don't find the murderer, but they meet the two announcers.

"Where is he now?" asks a guard to the announcers.

"In the dining room."

"Did you see how he died?"

"No, we were outside and had no idea about it. We were surprised too!"

The guards call the medical staff. Within a minute, they come fully equipped with many sorts of tools.

"From his body's condition, what we can obtain is that he died of poison," says the chief forensic.

"Poison?" say the guards, surprised. "We have no poison here, how can he be poisoned? A boarding attack? The ship's shields are still up and working!"

"The kind of the poison is new to us, too. We think he's been murdered."

The guards call the detective.

"Tell me, what was the captain doing?"

"The captain was drinking tea in his dining room, as always. Neither of us accompanied him, nor did any other crew member."

"How often does he do so? I mean, without company?"

"Every day. I mean, those clocks show the same time every 24 hours, don't they? He tells us to exit."

"Did he show signs of depression or sadness recently?"

"Not at all," says one of the announcers confidently, "let alone after that control ship was destroyed!"

"So yes, the captain has been murdered," concluded the detective, "escort me to the surveillance room."

Later, in the surveillance room...

"Hey! Why are you sleeping on your job? The captain's been murdered!"

The surveillance officers are fast asleep. The guards wake them up manually.

"What? Guards? What's going on?"

"The captain's been murdered! Why were you asleep?"

"Asleep? What?? The captain was murdered??"

Suddenly another guard exclaims, "I've found something!"

"A gas grenade? What really is going on??"

"Hey, this is a sleeping gas grenade! There's some kind of timing circuit too!"

"I think... they have discovered teleportation technology."

The detective and surveillance officers browse through the surveillance camera records. They find no instances of someone suddenly appearing. Furthermore, they didn't find anyone with a strange or unusual clothing.

"It was planned. Very planned," remarks the detective, "and their teleportation technology is very accurate. They can pick the right spot so that the murderer can kill a crew member and steal his clothing."

After a lot of work, the detective has found 3 possibilities:

  • The first was dressed as a janitor. He wiped the chair and table on which the captain sat, and washed the cup used by the captain (and other cups and plates). He did so about 40 minutes before the captain was found dead.
  • The second was dressed as a food inspector. He was inspecting the food in the dining room. He did so about 1.5 hours before the captain was found dead.
  • The third was dressed as a water supply system engineer. He was caught on camera fixing a leak in the pipe which supplies water to the dining room. His body was such that the camera couldn't catch his tools. He did so about 5 hours before the captain was found dead.

He found nothing suspicious about that information. The janitor cleans on schedule, the inspector inspected on schedule, and the pipe actually leaked.

The three are brought before the detective for questioning.

"Do you know each other?"

They look at each other for a while and answer "no". Shortly afterwards, the second noticed the janitor was different. "Hey, you're not any janitor I've seen," the second says. "Perhaps he's a replacement?" the third says. "You're right, I was transferred from another ship. I replaced a janitor who died of a heart attack. This is the flagship anyway, I understand why I was brought here."

"What were you doing 20 minutes before the captain was found dead?"

The first answers, "I was cleaning a bathroom in the control section."

The second answers, "I was at my quarters, because I have completed the entire inspection schedule today."

The third answers, "I was fixing another leak, on a pipe supplying water to the quarters."

"Still inconclusive," thinks the detective. "Guards, call the other detective."

"You" are brought into action. You ask them, "Now I'm asking you all a question about this ship. What is the name of this ship?"

"Wielder," answer they nearly simultaneously.

"How old is this ship?"

The first answers, "15 or 16 years."

The second answers, "9 or 10 years."

The third answers, "It's 20 years old."

"How many guns does this ship have in total?"

The first answers, "About six thousand guns."

The second answers, "There are five thousand five hundred guns."

The third answers, "He was correct, there are five thousand five hundred guns."

The other detective then asks you, "What do you think? Is there enough information?

Who do you think is the murderer?"

  • $\begingroup$ I have a hunch it has something to do with the numbers in every paragraph (except for the surveillance room)... No idea what though. $\endgroup$
    – Lolgast
    Commented Jan 30, 2018 at 14:32
  • 1
    $\begingroup$ This might be nitpicking, but I could answer that any of the 3 is the murderer without giving any rationale, and I'd be right, since the question is "who do you (I) think is the murderer?" and not "who is the murderer?" :-) $\endgroup$
    – Phylyp
    Commented Jan 30, 2018 at 17:16
  • $\begingroup$ If the enemy can teleport with such great accuracy, why bother with a human infiltrator at all? Just teleport the poison right into the captain's cup. Or better yet, teleport the captain somewhere else (like jail. Or the vacuum of space). $\endgroup$ Commented Jan 30, 2018 at 21:19
  • $\begingroup$ @Bachrach44 1. not accurate enough for that, 2. they want t gather information (the murderer carries a communication tool) 3. the teleportation technology only teleports what is in the "box" which is in their ship $\endgroup$
    – user351579
    Commented Jan 31, 2018 at 9:25
  • $\begingroup$ @user_194421 Care to elaborate? There is nothing about a "box" in the riddle narrative. In fact, neither are the details of teleportation technology explained (i.e. the precision and capability), nor is the fact that someone concludes from finding a timer and a gas grenade that the enemy must have discovered teleportation technology, which actually sounds like a pretty far fetched conclusion. How did the traitor come aboard with the poison? Why could they not simply bring the grenade and the timer the same way? $\endgroup$ Commented Jan 31, 2018 at 18:15

6 Answers 6


I think that the murderer

Disguised himself as a food inspector.

How I came to this conclusion:

The "food inspector" distracted us from suspecting him by pointing out that the janitor wasn't the same as usual, he could deduce that from the fact that when asked, the engineer said that he didn't know that person. This technique is typical of someone that doesn't want the attention brought to him!
The killing blow is that when asked the number of guns on the ship, he could give a precise answer, that was confirmed by the engineer. Now, it would be the job of the engineer to have such knowledge about the ship, but a food inspector? I don't think so, which means this identity is not his true one.

A few afterthought to confirm my suspicions:

The engineer cannot have poisoned the captain, because using the water as a conveyer for the poison would've hit the janitor as well.
The food inspector is the only one which actions 20 minutes before the crime cannot be confirmed, he could've been reporting to the enemy or sleep-gasing the surveillance team.
Lastly, when asked how old the ship was, he answered with an unexpected low age, explained by the fact that his faction only learned about the existence of this ship few years after he's been built.


I believe the captain was poisoned by....

The first person (the janitor)


The inspector only looked at the food. The captain was drinking tea, not eating. The Third person (the engineer/plumber) was fixing a leaky pipe five hours beforehand. If he had inserted the poison then, it would have all been used up when the janitor washed the plates and cups, and the captain would have filled his cup with non-poisoned water.

  • $\begingroup$ Don't forget that there was a timing device with the grenade. Doesn't have to be the only one deployed. $\endgroup$ Commented Jan 30, 2018 at 23:39
  • $\begingroup$ @KarstenKöpnick If there was a poison dispenser connected to a timer, it would have been found. $\endgroup$ Commented Feb 1, 2018 at 5:52

I don't really have any damning conclusions, but I'd assume

number three, as he knows exact answers, while the other two are unsure, as if he had been intensively briefed. One could argue that their training might consist of ship history, but this is unlikely as he was the odd one out.

Just a hunch anyways.


My guess would be

The first one(janitor)


He was the one who was at the dining room last
He was the one who was not recognized when all 3 met each other
He only cleaned the chair and table where captain sat(which was probably his fixed place), but he did all the plates and cups since they may all use same cups and plates, so there is no captain-only cup
Also, "about 6000" is pretty close, but not exact number. I do believe that enemies were not able to get the detailed info about the Wielder(which should be classified), so they probably used photos to guesstimate the age and number of guns, etc.
Lastly, I do not believe there is a bathroom IN a control section. There could be one near to it, but not IN it.


It was

the janitor

He was supposed to be

cleaning which would require water


the engineer was fixing the pipe that supplies water to the captains quarters and so the water would not have been running. So he must have used poison instead of water to wash the captains cup.


It is not the engineer.

If the engineer was the one who put the poison into the water supply, he would have possibly killed the janitor and other people who got in contact with the vicious water before the captain was killed. So to commit the murder like that would base on sheer luck.

But the engineer was too smart to have such a stupid plan like that (he acts precise and he is very wise - a perfect person). His answer were always accurate and sounding confidently during the all the three questions ("It's 20 years old." is not even an approximation). He would not want anybody to die before captain to makes him put up guard. The janitor is at real risk of being killed here since he was doing the washing stuffs.

So the murderer was either the janitor or the food inspector. Also, the water is clean.

(Here I could not derive any logical reasoning about who the real killer is. And I was procrastinating and lost all of my attention to the puzzle. And it was a really tough day for me, so I'm turning this into a detective story instead, by letting my imagination wander. I hope you would find it to be interesting.)

I had two questions: "HOW THE ANNOUNCERS KNOW THE CAPTAIN HAS DEAD?" and "WHY WAS SOMEBODY PLANT THE TIMING GAS-GRENADE IN THE SURVEILLANCE ROOM?" Well, I have an hypothesis: Why was there a gas-grenade if the camera tapes has shown nothing wrong? The surveillance officers always stay in their room, so this would mean that there is something suspicious in the video. The answer is that the surveillance videos were edited by someone. I have reasons to suspect that the edited part has recorded all the action of the murdering. Also, this requires more than one person to accomplish (to both kill the captain using the poison and editing the video tape himself).

My hypothesis is that before the food inspector was doing his shift and going to rest for the rest of the day, the water supply engineer (THE MASTERMIND) went to fix the water supply at the dining room. He was carrying a gas-grenade and poison. After the engineer has fixed all the pipes and leave the poison in between the pipes (He did it while hiding from the camera as told), he would sneak into the surveillance room to plant the grenade. An announcer (MISS A) would goes to the surveillance room to start editing the working of the camera recorder. While her partner (MISS B) stayed at the announce room to make it less suspicious (What happened if nobody was in the bridge when somebody suddenly comes in?). Next, the engineer would go back to the quarter continuing his works to avoid suspicious. The JANITOR would finish his shift at the dining room, go to the place the ENGINEER has left the poison, take it and then put it the tea intended to be drank by the captain in the next 40 minutes (this was happening while the video was edited, with the help of MISS A). After that, the JANITOR went back to his normal work to avoid any further suspicion. MISS A stayed and kept watching until she was sure that the captain was poisoned to dead. Finally, she left went back to the announce room where MISS B was waiting and then...


"The captain's dead! The captain's dead!",

shouts someone from the bridge into a microphone, which catches it and spreads it all over the ship...

  • 1
    $\begingroup$ From the description I took it that the captain had his tea at rather precisely the same time every day, even amidst a fight. So that's highly predictable behavior. And given that the gas grenade had a timer, why shouldn't a poison dispenser have one. - Anyone any thoughts on that? $\endgroup$ Commented Jan 31, 2018 at 18:06

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