text: The next clip was from a camera in Wing A. The camera was mounted at one end of the large area. It showed an aisle flanked by workspaces on the left and a series of common areas—kitchen, breakroom, open discussion spaces—on the right. At the far end of the view was a line of glass-walled cabins and conference rooms which separated the other half of the wing. A passage in front of these rooms led to the linking corridor for Wing B on the right and into the reception on the left—both beyond the borders of the frame. An exit sign hanging above the passage was the only bright spot in the grey picture.
  
  Like in the beginning of the previous clip, nothing moved for the first few seconds. And then suddenly, something darted into the aisle from the left. It was a black disc, the size of a dinner plate. It moved back and forth on the floor for a few seconds before disappearing into the cubicles again.
  
  "It's the vacuum bots cleaning the carpet," Dan informed us.
  
  "Where's the sound?" Troy said.
  
  "The workspace cameras don't record audio," Dan said.
  
  "Really now?" he said, sneering.
  
  "It's supposed to be that way. For employee privacy," I interjected before Dan could reply.
  
  Troy started to say something, but was cut short by fresh movement on the screen. A glass door on the right, sliding open. It was the door that led to the restricted area. Only key staff were allowed beyond this point.
  
  A shadow crept into the aisle, dragging along with it the robot on the wheelchair.
  
  The robot moved around the space, spray-painting the two other cameras in that part of the floor. He then went right, down the passage at the far end, and eventually disappeared into the corridor going to Wing B.
  
  "He paints over the cameras in the other wing too," Dan said.
  
  "Gee thanks, we'd never have guessed," Troy said. "Tell me this, genius: how did he get the door to open? Isn't it supposed to be locked?"
  
  "That's right," I said. "You have to pass a retina scan and a voice check to move in and out of the restricted area. You can see the scanner right there, next to the door. What happened, Dan?"
  
  "It's the bots," Dan said, barely audible.
  
  "Huh?" Troy said.
  
  As if prompted, two disks and a trash-collecting spider marched as a group into the aisle and then scurried off in different directions.
  
  "The doors are unlocked during carpet cleaning… so that the bots can move about freely," Dan confessed. "The motion sensors are turned off as well. That's why they didn't raise an alert when Raphael tore down his room."
  
  "This is grade-A bullshit!" Troy cried, slamming his fist down on his desk. "Are you saying anyone could have walked in during this time?"
  
  "No…. It's not like that at all. I, uh…"
  
  "Are you gonna faint on us now? Speak up, man!"
  
  I honestly believed he might have, if Valery hadn't cut in. "Only the interior doors are unlocked," she explained. "The main entrance is still locked—it's beyond the exit sign you see in the far left corner. So are the fire exits and the windows. If someone tries to force their way in—or out—the alarms attached to them will still go off."
  
  "Someone already inside can still go wherever they please. Still a bad setup," Troy observed.
  
  "No one is supposed to be inside. Employees have to get special authorization to be allowed in on weekends," I said, trying to give poor Dan a leg up.
  
  "The cleaning lasts sixty, seventy minutes tops," Dan said, slightly encouraged by our rallying to his support. "These bots have distributed intelligence—they work in teams to get the job done faster. We use them in a lot of Halicom facilities."
  
  Dan had brought them in after the acquisition; we had people doing that job before.
  
  The robot was now back in Wing A. His last stop was the camera whose feed we were watching.
  
  "He sure knows his way around," Martinez remarked.
  
  Out of the corner of my eye, I saw Jane shake her head at me. Don't take the bait, she whispered.
  
  "Next, we have the recording from the server room," Dan said as he stopped the clip now gone dark and played the next one.
  
  The camera in the server room was right opposite the door. We saw the doors slide open as the robot wheeled inside. He ignored the camera and went straight for the racks, with the camera swiveling and following him. There were three rows of racks; arranged like bookshelves in a library, they extended the length of the room. He travelled along the left-most rack, a shadowy wanderer in a forest of blinking LEDs. He didn't have to go too far. He stopped, extended his arms to a shelf that was slightly above his head level, and grabbed a box. He lifted it up and twisted it around so that he could see the back. He then pulled out a cable from one of the ports in the back. This done, he put the box back on the shelf.
  
  "That's the ACS—the Access Control Server," Dan explained. "It has the permissions database for the facility. He just pulled out the cable connecting it to the wireless AP, the white device you see affixed to the column behind that rack."
  
  "English please," Troy said.
  
  Martinez stepped in for Dan once more. "The access control server stores building access related information: biometrics, key-card info, who has access to which area, and so on. The card swipe machines and biometric scanners at the doors get their data from this server. When he unplugged the cable, he severed the connection to these devices. It means the card readers and the scanners can no longer talk to the server."
  
  "Is that how the thieves got in? Because the card readers got disabled?" I asked.
  
  "Not really… No. I'll come to that," Dan said evasively before resuming the clip.
  
  The robot was now travelling along the center row. He stopped near the middle of the room and pulled free another box from its dock. This time he unplugged all the wires. He returned with the machine to the open space near the door.
  
  We could see him much more clearly now, as he was facing the camera. He had discarded the Iron Maiden t-shirt he was wearing earlier and was naked from the waist up. The silicone skin covering his torso was unstapled, the flap hanging loosely off one edge. Lights glowed in the cavity below: blue, yellow and red. The metal plate that was supposed to be covering the cavity was no longer there—this was what he had unscrewed back in the crèche room. Resting on his lap was the drill kit case he'd got from the scan room. He opened it.
  
  Raphael plugged the tool to a nearby power outlet and used it to unscrew the casing on the server box. Then, he took out the screwdriver bit and replaced it with a drill bit. He turned on the tool once more and applied the drill to the electronics inside the server.
  
  "That's the Network Video Recorder," Dan said. "Every security camera in the building streams its feed into the NVR. He just destroyed the hard drive."
  
  Troy said, "Wait a sec… If he destroyed the recordings, where is all this coming from?"
  
  Dan paused the clip. "The cameras have internal memory. They can store up to forty-eight hours of footage. After locking down the floor, I went around the building and swapped out the memory sticks from the cameras. So that they wouldn't be overwritten. If it was recorded after Saturday morning, then we have it."
  
  "Good thinking, Dan" I said.
  
  "Are you gonna give him a gold star too?" Troy said. "We just got lucky because your AI slipped up. Obviously, he didn't know that the cameras have their own copies of the recordings."
  
  Martinez cleared her throat. "He must have. Why else would he waste time painting over the cameras? If he was anyway going to destroy the recorder…"
  
  "Hmm," Troy said, pondering over it. "You are right, I didn't think of that. Why indeed?"
  
  "Which raises another question: why destroy the recorder?" she said. "The only way he could make sure we learnt nothing of what transpired that night was to destroy both the recorder and the memory sticks in the cameras. Destroying the NVR alone serves no purpose—at least none that I can think of."
  
  "The cameras are all fixed on the ceiling. The robot would need a ladder to reach them and destroy the memory sticks. Not to mention legs. So he took the next best option and spray painted them," I offered by way of explanation.
  
  "Still doesn't justify all the trouble he took to break the recorder," Martinez shot back.
  
  Dan jumped in. "It gets stranger. Disconnecting the access control server doesn't serve any purpose either. The front doors will remain locked even when the card readers cannot talk to the server. It's a safety measure, you see—we don't want the doors letting anyone and everyone through if the access server crashes for some reason."
  
  "When I swipe my card at the front door, doesn't the reader look up the access server?" I said.
  
  "No. It checks your credentials against a local copy of the access list. All readers and scanners have a local copy of the database stored in their internal memory. It's not a problem because the master database on the server is flashed to the devices every thirty minutes. That way they always have the latest version."
  
  "If an update was made to the access database on say, Friday, the devices would all have that update?"
  
  "Yes. As I said, the list is refreshed every half hour."
  
  "And as the systems admin, only you can make changes to the access database, right Dan?" I said, meant more as an observation than a question.
  
  "Yeah, but—"
  
  "Did you make any changes on Friday?"
  
  "I don't understand how it has any relevance to—"
  
  "Did you or did you not, Dan?" Troy drawled at him.
  
  "I didn't make any changes on Friday. I tell you, changes are not that frequent. The last update to the database was more than a month ago, when we took in some additional staff from our other offices."
  
  "Why do you think he pulled out the cable then?" I asked.
  
  "I don't know. The only thing that occurs to me is if an employee were to enter the premises at the time, there wouldn't be a record of it. The card readers do need to be connected to the access server to log staff entries and exits. If the ACS was offline, there would be no entry."
  
  "Are you suggesting one of our employees stole the core?" Troy said.
  
  Dan hesitated, then glanced at Martinez. "No," he said after a moment's silence. "As Andy mentioned before, no one is allowed inside the office on the weekends. The card readers are programmed to keep the doors shut unless an employee has a special pass. That's why Sheng was not able to get inside today. The reader at the front door didn't know it was Monday, since it was no longer talking to the server from which it gets the date and time. So it denied entry to all cards, which is the default setting for the weekends."
  
  "Did you issue a special pass to anyone last week?" I asked.
  
  "No."
  
  "Maybe you issued one before and forgot to deactivate it?" I suggested.
  
  "No," Dan protested. "The passes are valid only for twenty-four hours. They are automatically deactivated after that."
  
  "Looks like we have ourselves a mystery. Two mysteries, actually," Martinez remarked.
  
  "Enough," Troy said, cutting in. "I think we are reading too much into the actions of the robot. Maybe he did what he did because he didn't know better. Let the cops worry about it. On with the rest of it."
  
  Dan restarted the video.
  
  The robot, having completely destroyed the video recorder, tossed the power tool on the floor. He reached into the tool case and took out something that reflected in the dim light. It was a shard from the mirror he had smashed before.
  
  He turned on the lights in the room. Using the mirror to see inside the cavity, he started plucking at the wires inside.
  
  "Those blinking lights the core?" Troy asked.
  
  "No. Just various connectors and electronics for the robot body. The core is beyond the tangle of wires, a box about this big," I said, cupping my hands around an imaginary grapefruit.
  
  "And one can just detach it and take it away?"
  
  "If the core is already shut down, then yes. Precautions must be taken while disconnecting the power supply lest you damage the core's internal circuitry, but that's the general idea. You have to understand, we designed the cores to work with a test frame. Raphael didn't like it, so we got this retail sex bot and customized it to house the core."
  
  The robot stopped his activity almost as soon as he'd started it. He snapped his head up at the camera, as if he had just realized it was there. His final act was to hold up the can of paint and blind the camera, but not before giving us what seemed like a long, thoughtful stare. It was almost as if he was trying to say goodbye.