Killing Time On Mars

by Alec Taylor

  “Where should we start?” he asked.

  “Let’s have a look at the map of the colony,” I replied.

  He opened a map. I dropped a pin on the location of Imani’s body and another on the airlocks to greenhouses three and four. Then I dropped one on the airlock to the inner colony.

  “What have we got there?” I asked.

  “Eyes and ears on the outer door, nothing on the inner door.”

  “Let’s have a look.”

  Liu opened the camera on the outer door and we could see a colonist walking up to the door. Their hand and arm went out of picture as they pressed the open switch and a second later they went into the airlock.

  “Can we see the archive of the day we were talking about?” I asked.

  “What time?”

  “Start at 23:00.”

  Liu opened the archived footage and pressed play. We watched for a few seconds and then he sped it up. Eventually, a single person went out through the airlock. Two minutes later, somebody followed them.

  “Is there any way of identifying someone from their walk?” I asked.

  “Mmm…Maybe. I’m not sure how distinctive a walk is. The best way would be to have footage of all the colonists walking with their helmets back, so we could identify their faces and link them to their walks.”

  “Do we have that?” I asked.

  “Um…don’t know.”

  “Do we have any cameras inside the colony?”

  “Thousands, but they’re all on suits or devices. There are no dedicated cameras.”

  “None of the internal doors have cameras,” I said, thinking out loud. “And there are none in the passages. We didn’t need them for security.”

  “No.”

  I was staring at the killer on the screen, recorded in time. No door cameras, I thought. Only suits and devices.

  “Any devices with cameras pointing toward the passages?” I asked.

  “I don’t know, but if you find one, I might be able to find its archive footage. If it hasn’t been wiped yet, that is.”

  “I’m going for a walk,” I said. “I’ll be back in a few minutes.”

  I walked out to the main airlock, looking left and right. As I walked back, I searched for devices with cameras that might see out into the passage. Most of the rooms had doors but no cameras. And then I got to the dining room and stood in front of the open arch. To the right of the doorway was a memorial for the three colonists killed in the dining room incident. The serving table used to sit there, I thought. I looked at the serving table in its new location on the left—perched on the far end was the medicine dispenser, and a rush of adrenaline ran through my body. A tiny camera lens was sitting on the top left of the machine. I imagined it on the other side of the room and realised that, from the dispenser’s old position, the camera had probably covered the passage. I rushed back to Systems.

  “I might have something,” I said to Liu. “Maybe nothing. The medicine dispenser—can you extract old footage from it?”

  “We’ll see,” he said and dug around on the network for a little while. Finally, he said, “Here it is on the local cloud. There’s a mass of data in the archive; you might be in luck. What now?”

  “Okay. Same day, a few minutes earlier, starting at 23:00 again. Let’s have a look at the footage.”

  It took Liu a few seconds to upload the data and find the right timestamp. He opened the footage, and I nearly jumped for joy. The image was distorted at the edges, but it was in high resolution, and it clearly showed the entire width of the passage outside the dining room. The dining room was dark, but the passage was lit.

  “Come on. Show us,” I said.

  Liu pressed play and then sped up the footage. One person went out. And then, around midnight, two people—both with their visors down—walked calmly down the passage from the airlock toward the dorms.

  “What the hell?” I exclaimed.

  “Were you expecting to see two people?” asked Liu.

  “No.”

  “Somebody was waiting up near the airlock. Keeping the coast clear, maybe?”

  “Yes, I guess so.”

  “But we have no way of identifying them.”

  “No. Let’s rewind from 23:00.”

  Liu restarted the footage, and we watched as it went back in time. We suddenly started seeing people leaving the dining room.

  “So they were up there all along?” said Liu.

  “I guess so,” I replied. “I don’t get it, either. They were waiting up there all evening. Perhaps they were in the greenhouses. We need to identify who goes out and who comes back.”

  “Hmm…” said Liu.

  “Hold on. Let’s think this through,” I said. “We have a record of everyone who went through that passage in either direction the day before Imani was killed. What if we look back to a time when we can be confident everyone was in their dorms, then play it forward? We should be able to see everyone going out and everyone coming back. Most of them will have their helmets back, so we should be able to identify many of them.”

  “Yeah,” said Liu. “Okay, I might be able to do that, but it will take some work. I’ll have to write an algorithm to correct the distortion in the corner of the lens, and find another algorithm to match faces to bio photos, but they should both be relatively easy. Then I’ll need to somehow log the departures and arrivals, separate them from people visiting the dining room, then account for the unidentified people. Yeah, this might take a while. Why don’t you leave it with me.”

  “Okay,” I said. “Go for it.”

  That night, I went to the lounge for the first time since the overdose. Nobody seemed to care about my incident anymore. Liu didn’t turn up; I guessed he was still working on the video data.

  The next day was Sunday, so I tried to sleep in. I lay in my bed, looking at the ceiling and wondering how Liu was going. Then he called me around 08:00 and asked me to come to Systems.

  As I walked in, I said, “Please tell me you’ve had some sleep.”

  “A few hours,” he said, then smiled sincerely and added, “I haven’t had a puzzle like this for ages. I’m really enjoying it.”

  “That’s nice,” I said, but he missed my sarcasm.

  “So, listen,” he said. “I’ve done the first part and then had to add on another matching algorithm.”

  “Slow down, Liu. I’m a long way behind you.”

  “Okay. So, the identity matching was fairly straightforward but not very helpful. Most people are looking the other way as they walk up the passage, and lots of people still have their visors on when they come back. We’re not going to have a good database of walking styles, and I’m not sure there’s enough variation anyway. But then I ran the in-out algorithm and started it at 03:00 in the morning the day before Imani was murdered. It took some juice, but the system smashed out the results, and after the two people return after midnight, the number of outs is equal to the number of ins. Except for Imani, of course.”

  “You mean, the same number of people leave as return?” I asked, struggling to keep up with him.

  “Exactly. Anyway, that’s not very helpful when you can only identify a small number of them. So I started thinking about where they were going, and I started matching the airlock footage to the dining room footage to see where they went. I found something interesting.”

  “What?”

  “Three people don’t go out the airlock when they pass the dining room.”

  “What do you mean?”

  “Well, for example, I saw you visit the Security Office in the morning, and then I actually identified you leaving around midday. You never went out the airlock into the outer colony.”

  “Okay…”

  “Okay, so this is where it gets weird and actually really simple. I ran a program to match people going past the dining room and through the airlock. Here’s the thing: apart from you, there were two people who went past the dining room but not out into the outer colony. There are no geo-location tra
nsmissions in the log for them, but you can actually see them going past the dining room.”

  “But not out through the airlock?”

  “That’s right. There are only two places the killer and their accomplice could have been—Security or the Executive Office.”

  34. THE COUP

  I stared at Liu for a moment, turning it over in my mind. We were circling in on the answer and I wanted to double-check everything.

  “Okay, wait a second,” I said. “Can you show it to me?”

  “Sure. Pairs,” said Liu. “My algorithm matched colonists going through the airlock to a colonist walking past the dining room a few seconds later, and vice versa. Every colonist who left or entered the inner colony has a match at the dining room. Look.”

  He showed me three columns of data. The first two cells contained pairs of timestamps, each about 30 seconds apart. The third column was partially filled with colonist names, where the facial recognition could identify the colonist. Liu asked me to randomly choose a row—I did, and he found it on both sets of video recordings. He ran them both forward, side by side on the screen, and I could see a colonist enter through the airlock and then pass the dining room a few seconds later. I randomly chose two more to check and they matched the data.

  “So, apart from those two missing colonists, and you,” said Liu, “I have a match for every colonist who goes past the dining room with a colonist who goes out into the outer colony. I then tallied up the number of colonists who go out with the number who return, and they’re equal. Everyone who left came back. Those two who didn’t go through the airlock didn’t come back past the dining room till around midnight.”

  “So…two people were waiting in Security or the Executive Office the whole evening.”

  “Yeah. Was anyone else in the office when you went there that day?”

  “I can’t remember—but then, I don’t really remember going there at all. It was months ago.”

  “Well, I can tell you nobody else was there. After you left Security and walked back past the dining room, the two people walked out past the dining room but didn’t go through the airlock—one around 15:30, the other around 16:00. There are only two places to wait between the dining room and the airlock, and they’re Security and the Executive Office.”

  “You don’t suppose they were careless enough to log on while they were there?”

  Liu quickly looked up the records for logins on the screens in both Security and the Executive Office, but he found none.

  “What now?” asked Liu.

  “Calls,” I said. “Let’s see if either of them made any calls that can help us to identify them.”

  “Right,” said Liu and looked up the log of calls for the screens in the two offices on that day.

  “Look,” said Liu. “There was a call to this screen in the early evening.” He pointed to the last data point.

  “Which screen is it?” I asked.

  “Here,” he said, opening a systems plan for the colony and zooming in on Security and the Executive Office. “It’s…that one…”

  “That’s Karl’s screen,” I said.

  Liu looked at me with shock spreading across his face. One of the two unidentified colonists had received a call on Karl’s screen the night Imani died.

  “Hold on,” I said. “Just because Karl’s screen received a call doesn’t mean he was there. Anyone can answer a call on a screen.”

  “Right,” said Liu, looking relieved but also almost disappointed.

  “How long was the call?” I asked.

  “Um…about a minute.”

  “And where did the call come from?” I asked.

  “Give me a second,” said Liu as he searched the network. “Okay, here it is. It came from Karl’s suit. Huh?”

  I furrowed my brow in confusion.

  “Oh, wait,” he continued. “The call originated from someone else and was diverted from Karl’s suit to his screen…It originally came from…Jan’s suit.”

  “So…Jan called Karl’s suit, but it was diverted to Karl’s screen, where somebody answered it.”

  “Yeah. Karl must have diverted calls from his suit to his screen.”

  We stared at each other for a few seconds.

  “He made a mistake, didn’t he?” said Liu, raising his eyebrows. “He answered a call diverted from his own suit. He was there!”

  “Um, no. That doesn’t prove it was Karl,” I said. “It was a diverted call to his suit, but we still don’t know he answered it on his screen.”

  “But surely…” said Liu.

  I started thinking through what we had. There wasn’t enough to make a firm case. We needed something concrete linking Karl to his office—I considered asking Jan if he could remember making the call to Karl. However, I didn’t trust him at all and I suspected that he might even have been involved in the murder somehow.

  I was also troubled by the way we had collected the evidence.

  “Hold on, Liu,” I said. “We don’t really have enough here to implicate Karl, although we might confront him. One problem is, we collected the evidence from native systems, without any kind of warrant or due process.”

  “What do you mean?” asked Liu.

  “I mean, we didn’t have permission to go digging for this information and the way we interacted with the systems wasn’t controlled or recorded. If we ever went to a court, the evidence would be unreliable. Not that I have any idea which court we’d go to.”

  “Yes, but it looks to me like Karl killed Imani!” said Liu.

  “Well, there’s another complication,” I replied. “There were two people waiting out there. Assuming we can get Karl to confess to being there in his office, which I sincerely doubt, we can’t prove which one of the two colonists actually did it. Unless…How tall are they?”

  Liu looked up his bio and said, “Karl is one hundred and seventy-one centimetres.”

  “And how tall was Imani?” I asked, already knowing the answer. A chill washed over my entire body.

  “She was…one hundred and seventy. Weird.”

  “Let’s look at the footage of the two colonists walking back around midnight.”

  Liu froze the image and it was obvious that one of the colonists was taller than the other.

  “What is it?” asked Liu.

  “I triangulated the heights of the two people who walked into the greenhouse the night Imani was killed. They were so close that we couldn’t be sure whether Imani walked in first or second.”

  “Oh…” said Liu. “Does that mean…Are we saying that Karl murdered Imani?”

  “I think so,” I said, shocked. “But we still can’t prove it.”

  “And someone else was there as well, someone taller?” said Liu, his eyes wide.

  “Yes, someone was with him.”

  We stared at each other for a moment, reeling from our revelation.

  “What do we do now?” asked Liu.

  “It’s very tricky,” I replied. “If we’re right, we can assume Karl’s capable of murder—anything, really—and we’ve been having this conversation in front of several machines that could be spied on.”

  “That’s not likely. I have some active countermeasures in place.”

  “Regardless, I think we should act quickly.”

  “And do what?”

  “I think we should enlist some help and then show our hand. We’ll call in some people we trust, and then we’ll confront Karl with the evidence you just showed me. If we do it right, he might just implicate himself.”

  “And then what?” asked Liu.

  “I don’t know. One step at a time.”

  “So who do we call?”

  I knew exactly who to call. The people I had made a pact with in the outpost at Valles Marineris.

  “Tony, June, and Vivian to start with. And also Chris, I think. We might need her infirmary anyway.”

  “Is that enough? Karl probably killed Imani with his bare hands,” said Liu, “and we don’t have any we
apons.”

  “We’re going to outnumber him.”

  “And then what?” asked Liu, a note of panic in his voice.

  “Where is he now?” I asked.

  Liu looked up Karl’s location. It was late morning by then and Karl was in his office, logged in, wearing his suit, and transmitting live geo-location and biometrics readings.

  “Okay, let’s call in the troops,” I said and called Tony, June, Vivian, and Chris.

  And then, like a flash, I had another idea. I also called Hu.

  *

  They all rushed to Systems when they heard the urgency in my voice. One by one, they filed into the room, and when they had all arrived, I asked them to disable their transmitters. It turned out that all of them had already disconnected, including Hu, which was even better—nobody knew they were with us in Systems.

  Then I laid it all out, from top to bottom. The camera on the medical dispenser, the recorded footage, the identification algorithm, my trip to and from the Security Office, the counts of people who had left and returned, the matching pairs, and the two missing people. Then we showed them the record of the call from Jan to Karl’s suit, which had then diverted to Karl’s screen. Finally, I showed them the triangulation of the heights of the two people walking into greenhouse three, and I told them Karl’s height.

  “What are you saying?” asked Chris, looking sceptical.

  “Well, I just don’t understand it,” said Vivian.

  Hu didn’t say anything.

  “Okay,” I said. “Basically, Liu found two people who walk out past the dining room but don’t then go through the airlock into the outer colony. Everybody else goes out and then later comes back through the airlock and past the dining room. Those other two people wait in Security or the Executive Office. They both then walk back past the dining room around midnight, after one of them has killed Imani. Now, we know that Karl had diverted calls from his suit to his screen, and someone using his screen took a diverted call from Jan, which lasted a minute. That’s too long for a wrong number. Jan was trying to call Karl and spoke to someone for a minute. I’m sure it was Karl. And Karl’s height matches the height of the killer on the video footage out at the greenhouse.” I paused. “We think Karl killed Imani.”