enough for a probable,” Naomi murmured. After purchasing their first analog spectrographs in the late 1970s, the CIA’s Directorate of Science and Technology had adopted, for lack of a better system, the forensic standards used by U.S. law enforcement at the time. A “probable” identification was assigned to any match greater than fifteen but less than twenty points on a given spectrogram. In other words, there was an 80 percent chance that the voiceprint in the MoD’s database matched the voice found on the tape in al-Umari’s Knightsbridge home.
Peterson was still trailing her finger along the screen. On the monitor, the voiceprint resembled the cross section of a series of waves. “See here,” she said, pointing to a large splotch of red in the left-hand corner of the graph. “That’s a hard c, like in the word ‘car.’” She moved over to the right-hand side of the graph, where the red was much less pronounced. “And this is a soft t, like in ‘booth.’ The fricatives you see here are really good news for us.”
“Because of the language difference?”
“Right. You tend to find a lot of allophones in the Arabic language, and they sometimes lead to false negatives on a spectrogram, even after you convert from analog to digital and filter out the elec—”
“Hold on,” Naomi said, a little exasperation creeping into her voice. “I understand the technology, Liz, but I have no idea what you just said.”
“Allophones?” Kharmai nodded meekly, causing Peterson to smile. It wasn’t often that her stubborn friend could concede when she was lost. “Well, a phone is a sound that has a definite shape as a sound wave, which is obviously really helpful when you’re trying to match voiceprints. An allophone, on the other hand, is one of several phones in a phoneme. If you change one phoneme in any given word, you can produce another word entirely.”
“So a phoneme is like…a syllable?” Naomi asked.
“Not really. More like the way in which syllables are put together. But as I was saying, the problem with allophones is that they can lead to false negatives. This happens for two reasons. First, the software is good, but it isn’t that good. It can’t always differentiate when two phones are that similar. Second, you’re always going to have some electronic interference. Part of this occurs when the recording is actually made. In this case, we had to deal with distortion on the recording device and interference on the line itself.”
“Also, you lose some of the source material when you convert from analog to digital, right?”
Peterson flashed Naomi the kind of smile a teacher reserves for her star pupil. “Exactly. We use filters to remove electronic noise outside of the desired frequency range, which helps, but you still lose some of the original conversation in the measurements.”
Naomi shrugged. “Eighty percent is good enough for me. What’s the background?”
The other woman minimized the spectrogram and double-clicked on the numerical file. Instantly, the screen filled with information.
“Voiceprint 243.55 belongs to…Abdul Rahman Yasin.” Peterson sucked in her breath as her eyes scanned the screen. “God, this guy is right up there. Wanted on nine counts by the FBI. Involved with the PMOI in Iran in the early nineties, suspected collusion in the WTC bombing in ’93…He matches your profile, Naomi.”
Kharmai leaned in to get a closer look. “Except for the languages. He doesn’t speak German, and he learned Arabic in Tunisia. That’s the Maghreb dialect, and we typed the voice on the tape as Gulf Arabic.”
Peterson shot her a sideways glance.
“What?” Naomi asked.
“You didn’t mention the German. Where did you get that?”
Kharmai winced. “Sorry. That came from the Babylon Hotel. We’re pretty sure this guy Kohl is the second voice, but it’s almost certainly an alias, because the Germans don’t have any contractors by that name in the region.”
“So he speaks Arabic and German. That should narrow it down.” Peterson cleared the screen and began typing in the new parameters.
CHAPTER 9
ALEPPO • LONDON
From across the crowded asphalt road, Erich Kohl watched as the young man finished his tea and left the coffee shop, walking north on Souq Khan al-Harir. Kohl returned the copper pot he’d been examining to a disappointed shopkeeper and followed at a leisurely pace, the cuffs of his loose cotton pants gathering fine dust from the street. It wasn’t difficult to trail the other man. Rashid al-Umari, he thought, still had a lot to learn about his new profession.
Kohl had arrived in the city two days earlier and had immediately taken up watch outside al-Umari’s small room south of the Citadel. It was countersurveillance, really; he knew exactly where the Iraqi was supposed to be, for he had been the one to formulate the travel plans, and the young man was not imaginative enough to deviate from his instructions. At least, that was what Kohl had thought until earlier in the afternoon, when al-Umari had walked out after three days in seclusion, blinking his eyes like an animal emerging from a long hibernation, and had set out to explore the city.
At the time, he’d been angered by the Iraqi’s inability to follow simple instructions. In retrospect, though, he could see that this was a positive turn of events. There were too many places around the hotel where security officers loyal to the West might have burrowed in. Had that been the case, even Kohl’s practiced eyes might not have been enough to pick them out of the crowd. With Rashid on the move, a watcher was forced to risk exposing himself, which put him at a distinct disadvantage. Fortunately, it did not appear to be a concern in this case; Kohl had been trailing the Iraqi for several hours now, and nothing seemed out of the ordinary.
On reaching the intersection, al-Umari turned right on Sharia al-Jamaa al-Umawi, passing the north entrance to the Great Mosque a moment later. Devout Muslims carrying their prayer rugs were already congregating on the hard-packed dirt of the parking area, smoking and engaging in idle conversation. As al-Umari made his way through the small crowd, Kohl dropped back, preparing to break contact. The younger man was clearly heading back to the Citadel, but…
Something was wrong. Kohl slowed his stride and tried to take in the larger scene. The crowd was building by the minute. The muezzins started up far overhead—not the muffled recordings found in so many Middle Eastern cities, but individual singers perched high in the minarets, the stone towers attached to the mosques. The day’s fourth call to prayer rippled over the city as the first singers were joined by hundreds more. With the mournful tones came the expected response; the crowd in the street continued to swell. His eyes passed over the scene: the wood-shuttered windows climbing above the pavement, the sand-stripped cars lining the curb, the faces sweeping past in the road. He was rifling his memory, searching for something, someone he had seen before. Nothing jumped out, but then he saw a dark head turning, tracking. He followed the gaze to al-Umari, who was just passing out of view, having found a shortcut through an alley framed by buildings of red stone. The man’s feet followed the gaze, stepping into the street, pushing through the throngs. There was something wrong with this dark, unlined face, Kohl thought. It was the face of a boy not yet twenty, too young for intelligence work. But those eyes were so intent, so focused.…
Kohl considered quickly. There was nothing professional in the man’s movements, though that could be intentional; he had seen it done before. One watcher was given away to draw a response, to distract the target, but he didn’t think that was the case here. Syria’s internal security apparatus was an ever-shifting maze of poorly
