Free Poison Most Vial by Benedict Carey Page A

lab. “Exactly, here’s what we have.”
    Ruby pulled a chair closer to the computer and began numbering doors to her diagram as Sharon read them off. “Remember, this is one person’s badge we’re following,” Sharon said.
    â€œRight, OK, here they are coming in, through D12,” Ruby said, staring at her diagram. “Then they would have to swipe their card to get the elevator down to the forensics department—that must be D7. And that makes D5, the next door, the one into the lab itself.”
    â€œWhoever it is,” Rex said, “they’re going out and coming back in D5, with D17 in between there—and once, D8.”
    Ruby put her head back and imagined the hallway outside the lab. Only two ways to go: through the door on the left to the kitchen area with the microwave, candy machine, sink, and coffeemaker. Or through the door on the right to the bathrooms.
    â€œVictor,” Ruby said.
    The others gave her a blank look.
    â€œOne of the grad students. He’s always going to that candy machine to get licorice to have with his tea. Like, it’s a ritual thing, every hour.” Ruby wasn’t aware that she picked up this pattern while sitting there doing her homework in the evenings. But now she was sure of it.
    So door D17 must be the door to the kitchen area. That meant that door D8 must be the one you had to go through to the bathroom. Ruby filled in her diagram.
    Sharon wrote down
Victor?
next to that badge number and plugged in the second number that Ruby had given her. “OK,” she said. “This person came into the forensicsbuilding at 5:13 P.M. and entered the lab a minute later . . . then, it looks like, they went out to the snack room. Right after they got there.”
    â€œLydia,” Ruby said. “Like, 5:13, that’s late for a Friday. Everyone else is in there by five o’clock, latest. She always got there late—dropped her stuff and went right out to get a snack. Those nasty jalapeño pretzels.”
    â€œRight, well, that’s not all she did,” Sharon said.
    After arriving that night, Lydia came back through D17 and D5 a couple of more times. Runs for diet soda, Ruby told them. The badge also passed through the opposite door in the hallway, D8, three times—for the bathroom.
    â€œNothing strange there, that looks normal,” Sharon said.
    â€œWait,” said Rex. “Go back to that part, around 7:12 or so. The bathroom door one.”
    â€œYep,” Sharon said, scrolling back. “There,” she said, pointing.
    D16 1901
    D8 1912
    D5 1912
    â€œD16?” Rex said. “Where’s that door?”
    Ruby made a guess. “On the other side of the bathroom there’s a tech room off the hallway. I was in there once;there’s a back door that leads to some stairs that go—I don’t know where. But I’ve never seen anyone else from the lab go in there.”
    â€œYou have now,” Rex said. “That’s more than ten minutes before she comes back through the hallway door. What’s she doing in that little tech room that long? I go in the bathroom fifteen seconds at home there’s someone at the door.”
    â€œThat’s because you got twenty people in that place,” said Ruby.
    â€œNine. And you be quiet. Least we don’t hang boxer shorts out the window to dry, like your dad do.”
    â€œYeah, well, if you guys didn’t tie up the dryers for five hours every day—”
    â€œWait,” said Sharon. “Think. Keep your heads in the problem. What is Lydia doing over there for so long? Could be no big deal. But it’s a great question.”
    Ruby checked the library clock and saw that they hadn’t been at the computer for much more than ten minutes. Eleven minutes was a long absence at that lab. She was surprised that her father hadn’t mentioned it.
    â€œHuh,” Ruby said. “Is there any way to check if