his disappearance, he ended up inside the coverage zones of three towers. Those towers’ zones overlap at an area roughly triangular, about two hundred fifty yards on a side. We know he was going to Optimo, and that makes sense. The Impierno building and the villa are both inside that overlapping zone.
“He did move in and out of that zone a couple of times, but he reentered it for the last time at 1106. During the next eleven minutes he received three text messages from his mother. No reply.”
Favor said, ”When did he leave that coverage zone?”
“He didn’t. Well, the phone didn’t. We can assume that the phone was taken away from him at some time that day, because at 1618 it transmitted the bogus text to his mother. Immediately after that, the phone went offline and completely off the grid. It hasn’t shown up on the network since.”
“Somebody pulled the battery,” Stickney said.
“Most likely.”
Favor said, “And Marivic?”
“We’ll need maps for this,” Arielle said. On the laptop Arielle pointed at screen captures made by Arturo Guzman, showing the path of Marivic’s phone through the cell system’s towers.
“Marivic did arrive in Manila. Records put her phone in two cells that cover the Philtranco bus station, followed by thirty-two minutes of apparently aimless travel through Pasay and Parañaque and Makati, the areas between the bus terminal and the airport, where she left Manila.”
Mendonza said, “She left Manila by plane?”
“Yes, but not by jet. The phone was picked up by towers at the southeast side of the airport, the general aviation area. Around 0610, the phone began to pass through a succession of cells south of Manila, spending three or four minutes in each cell and moving into the next one. Obviously it was airborne. It flew about one hundred thirty-five miles an hour, three hours and forty minutes, on a heading of about one-eighty true. This flight path took it over the island of Mindoro, across the Sulu Sea, to where it landed along the western peninsula of Mindanao, twenty to twenty-five miles north-northeast of Zamboanga City. It spent approximately thirty minutes on the ground before it took off again. Distance of the first hop was five hundred miles, more or less.”
“This sounds like a slow single-engine plane,” Mendonza said. “The half-hour stop would be for refueling.”
“Apparently.”
“Wait a minute,” Favor said. “Is there an airstrip twenty miles north-northeast of Zamboanga?”
“No.”
Stickney looked closer at the map.
“That’s a coastal area,” he said.
“Seaplane,” Favor said. “It wouldn’t need an airstrip. Just a dock. They were carrying her on a seaplane.”
“It looks that way,” Arielle said.
“Zamboanga … You’re getting deep into Muslim separatist territory,” Mendonza said.
“Correct. Everything south of Zamboanga is in the autonomous Muslim region. And that’s where it was headed on the second hop. It flew south over Basilan Island. Five towers on Basilan picked up the phone before it reached open water and fell off the network.”
“Fell off the network?” Mendonza said.
“Once the phone got over open water, there were no more cell towers.”
“And it was never picked up again?”
“Correct. The southernmost tower on Basilan lost it around 1130 that morning. It hasn’t registered on the system since.”
“Then the plane could have gone anywhere.”
“Oh no,” Arielle said. ”I’m pretty sure I know where the plane landed.”
She began to work with one of the maps on the laptop screen, anchoring the takeoff point above Zamboanga.
“It’s basic trig, and a little deductive reasoning. I used the records from the towers on Basilan. I knew the coverage zones, and I knew how long the plane stayed in each zone. I also knew the airspeed from the first hop—one hundred thirty-five miles an hour. So, putting all that together and knowing the start point, I was able to line out the plane’s flight path over Basilan, two hundred eighteen degrees, give or take a degree.”
She tapped a key, and a straight red line appeared on the map.
“Even knowing the direction, you can’t tell how far it flew,” Mendonza said.
“True. But the destination would have to be an island. And along that flight path, anywhere near it, there’s really only one island of any size.”
She zoomed in on the map, to the red line, and moved the view along the line until a single island appeared in the otherwise unbroken field of blue.
She switched to an online view, Google Earth, a satellite image. At first the screen showed just deep blue, but as she zoomed in, an island took form. It was mottled white and dark, roughly a