Commissioner nodded. “Exactly. Do you see this dart? It is the kind of dart that is fired by a compressed air ceramic gun. It is used in the spaceships to sedate violent rioters. The only difference is that we use sleeping darts, while the dart which killed Professor Olmedo obviously contained a lethal toxin.”
Qeta went around the table to have a better look at the dead man. In spite of his hundred and twenty kilos he knelt with great agility, aided by the reduced gravity of the Moon. “Could you establish the time of the death?”
“A couple of hours ago, no more,” Sukyung said. “Time is of essence in this investigation. As you know, in order to move through the many levels of Luna City and open certain doors, you need to employ your own magnetic key, which, according to the security level of the owner, allows entry in certain parts and not in others. But all accesses are registered by the central computer and, at least in theory, we should be able to track every person’s movements rather precisely.”
Qeta finished examining the corpse, then got up. The commissioner was looking at him hopefully. “Something is wrong, isn’t it?”
Sukyung sighed. “Dead wrong. The lab door was opened by the murderer with a false skeleton key.”
“False?”
“As false as it can be. Its code number which was registered by the computer doesn’t match with any of the skeleton keys which are used by the personnel of Luna City.”
“That would suggest a professional agent, wouldn’t it?” asked Qeta, while his eyes searched the room. “A ceramic gun which can foil the metal detectors, a poisoned dart which is not in the trick bag of the lunar police, a false skeleton key.…”
“This is just what we thought,” Sukyung confirmed the hypothesis. “But we have a possible track to follow.”
“Interesting,” commented Qeta. Now he had lifted his eyes and he was examining the ceiling. “And what is this track?”
Sukyung said smugly: “We can reduce the number of the possible murderers to three. Thanks to the use of the magnetic keys we can track the movements of all people rather precisely. Actually there are only three of them who did not leave a traceable path in the last four hours and so we are a hundred percent sure that the murder must be one of them. They are—”
Qeta stopped him with a gesture and pointed instead at the ceiling. There was a tiny electronic eye focused on them at the moment. “That is a security camera, isn’t it? I trust you have already checked the tape?”
If Sukyung thought the question was slightly insulting, he did not show it. “Sure. That was the first thing we did, but the range of the camera doesn’t cover the room completely and the murderer placed himself in a blind spot. From there he fired the gun without being filmed. I have a copy of the tape on one of the lab monitors. Do you want to see it now?”
“Please.” Qeta looked around him. He saw a turned on monitor on the left side of the room and started to walk in this direction. Suddenly he turned as if an idea had occurred to him, and came back to examine the table behind which the professor’s corpse was lying.
“Found something?” Sukyung came alongside him.
Qeta pointed at the table. There were five numbered glass jars lined up on the top and the last one was not erect as the others, but lay on its side. “I think Professor Olmedo was working on these specimens when he was killed. Apparently he was keeping the last jar in his hand and it rolled out the moment he was hit.”
“Right,” stated Sukyung. “You can see the whole scene on the monitor.”
The two men approached the monitor and Sukyung pushed a few buttons. Immediately the screen showed a movie of the laboratory. Professor Olmedo was behind the table and all of a sudden he raised his head with a baffled look in his eyes. A second later his look changed, but Qeta could not understand whether he was actually worried. It was almost sure the killer had just come in. Professor Olmedo might have sensed something was wrong, but either he was not yet sure, or perhaps he did not want to show he had understood what was about to happen.
The professor turned casually and from the shelf behind him he took a few jars and began to display them on the table. He acted as if he was not worried by the presence of the unknown visitor. Had he not understood that the intruder had come to kill him? His gestures were quiet and systematic; he seemed to prepare the jars for some kind of experiment. Nothing in his movements revealed he was afraid of being killed by the visitor.
“A shame there is no sound track,” said Qeta. “If we could hear what they said, it would be easier for us.”
Now the professor had finished arranging the jars on the table.
“Coming up now is the moment when he was shot,” anticipated the commissioner.
A couple of seconds later the face of the professor contracted while a ceramic dart pierced his jugular. The nerves of his face froze instantly and he appeared to gasp for air, then he collapsed on the floor.
“Paralysis with asphyxia,” said Sukyung. “He died almost instantly.”
“Go back a little with the tape,” said Qeta. “I want to see the scene again.”
The commissioner gave him a perplexed look, but he did not say anything and ran the images again. Once more the professor was shown to handle his lunar specimens.
“Ah!” Uriel Qeta exclaimed. “Just as I thought. Did you notice it?
“Notice what?” asked Sukyung. “I see the professor being hit while he is arranging the jars on the table and then collapsing after being paralyzed. Or did I miss anything?”
Qeta looked at him thoughtfully as if he was following a train of thoughts of his own. “If you observe the tape more carefully, you’ll notice the professor was not hit while he was arranging the jars on the table, but after he had already done with it.”
“So what?” Sukyung looked dumbfounded. “During or immediately after, what does it matter? It was the moment he was killed anyway.”
“Look at the tape again,” Qeta prompted the commissioner.
Sukyung sighed, but he ran the tape for the third time, and again there was the professor handling his jars.
“Stop the image here,” Qeta ordered him suddenly. “Don’t you notice anything out of order?”
Sukyung examined the image then he winced and turned to look at Qeta. He looked amazed. “I got it! How could I have missed it?”
Qeta nodded and pointed his finger to the fixed image.
“You see, at this point the professor has finished arranging the five jars on the table, but the last one did not roll out of his hand when he was hit. The fifth jar was purposely placed on its side by him! And then, only then, five or six seconds later, he was hit by the lethal dart.”
There was silence for a while in the room. Then Sukyung said slowly: “The professor understood his visitor had come to kill him and he left a message to us. To write it he used the only objects he had at hand at the moment, the jars with the lunar specimens.”
Qeta turned and went back to the table. “Let’s
