In my hotel room, I pulled up the computer files I’d been working on yesterday morning when I’d started comparing the geographical and demographic data with the timing and progression of the fires.
I’d been on the right track, just on the wrong, well… track.
I was typing in my scribbles when Lien-hua tapped at the door.
“It’s open,” I called.
“Aina can’t come.” Lien-hua had her computer with her. She sat on the edge of the bed and flipped her laptop open. “The 911 caller was a dead end, but she’s busy evaluating potential ignition systems from the previous fires. She gave me the codes.”
“Good. Give me a minute, then I’ll need them.” I clicked on one of the icons on my screen, and a map appeared with each of the arson sites marked by a small flickering flame. “See the placement of the fires?” I punched a couple of keys, and a series of red lines laced the city, highlighting the streets and highways of San Diego.
I traced one with my finger. “Roads.”
“Oh. Is that what they are?”
“Sorry. I’ll try to stop stating the obvious.” I tipped the screen so she could see it. “Now, if you look at the distribution of the fires, what do you notice?”
She studied the map carefully but shook her head. “Nothing.”
“Neither did I, until…” I uploaded the trolley routes and overlaid them against the map of the fire locations. A couple more keystrokes, and my computer-mapping program calculated the distances between the fires and the nearest trolley depots and flashed the totals in the lower left-hand corner of the screen. “See? The fires all occur within two hundred meters of a trolley stop, usually the Orange Line or the Blue Line.”
She gave a soft gasp of acknowledgment. “He’s starting the fires and then boarding the trolleys to get away.”
“I think so. Let’s check the timing. Look up the trolley schedule for me, and I’ll compare it to the times of the fires.”
She surfed to the San Diego mass transit site and read off the trolley arrival and departure times, and I punched them in. Hit enter.
A crisscross of lines appeared along with a detailed timing chart on the right-hand side of the screen.
“It fits,” I said.
She gave a long, soft whistle. “So, except for last night’s fire, each of the other fires was reported between five minutes prior to a scheduled trolley departure or eight minutes after the trolley left. How long would it take to walk two hundred meters?” she asked.
“I don’t know. Maybe three to five minutes. We also need to factor in the time it takes for the fire to grow, get noticed, and be reported. We can have some officers walk the distances to confirm the timing. But it looks like he didn’t park. He rode.”
“So, if that’s how he’s getting away…” Then it struck her.
“Access codes.”
“Right,” I said. “Every trolley depot is monitored by video surveillance. Let’s see how photogenic our arsonist is.”