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“But . . . ?”
“The Alberti Cipher is so simple,” Raisa said again. “It’s not complex; it doesn’t take an above-average intelligence to understand it. A computer would have been able to decode it, given more than three days. There’s nothing intellectually elegant about it. So why choose this particular one?”
Kilkenny hummed in thought. “I don’t know. That always seemed to get pushed down on the list of importance.”
Raisa nodded. She got it. Investigations were all about triage, and she wasn’t about to parachute in later and criticize every mistake. But as a linguist, she couldn’t help but be slightly appalled more focus hadn’t been put on the code.
“You all had an expert who worked on deciphering each of them, right?” Raisa asked.
“Yes, he never could make much headway.”
“No, I wouldn’t imagine he could,” Raisa said. The code was a simple one, but not when placed in a block like it had been. There was no way to cheat using short words and letters that often coupled up together. “Did he have any thoughts about the Alberti Cipher?”
“I don’t remember in particular,” Kilkenny admitted. “But I would think that means he didn’t. Nothing groundbreaking at least.”
Raisa nodded again, still staring at one of the letters from Conrad.
There was a crack in the foundation, she knew there was. And it was something she could exploit to bring the whole house down.
She just couldn’t see it yet.
Years ago, she’d watched a movie about Alan Turing, the man who’d broken the Nazis’ Enigma code—which had seemed impossible until it had been done. In one of the more cinematic moments, Turing was listening to two radio operators talk about how they recognized a particular enemy radio operator by the call signal he used—it was supposed to be random letters, but instead he used the name of his girlfriend. Turing realized that if they could isolate two or three words in a message theyknew was coming every day, their primitive computer could use pattern recognition to decode the rest.
They realized the Nazis sent a weather report at 6:00 a.m. every morning and signed offHeil Hitler.
Raisa closed her eyes.
With both codes, a handful of letters of gibberish kicked off each message, but then, without fail, they started the same way.
With Conrad, it wasMy dear Agent Kilkenny—or some other overblown salutation.
With their impostor, it wasDear Callum.
It was one of the first things she’d noticed about the different idiolects.
She’d thought it was their impostor making a mistake—or not even trying to mimic Conrad’s voice.
What if it served a different purpose, though?
Why me?Kilkenny had asked.
Why you?Conrad had taunted in one of those letters.
She stood and crossed to the door in three jerky strides. When the guard answered her knock, she asked, “Do you guys have a portable whiteboard I could borrow?”
The guard gave her a blank stare. “Um?”
“Shit,” Raisa murmured, and swung back to Kilkenny. “This is why a linguist was never a waste of resources. Text me if Conrad’s schedule frees up.”
“Wait, what are you—” Kilkenny called after her, but the rest of the question was cut off by the door.
Raisa didn’t slow, still clutching her tablet, where she had copies of both the encrypted and decrypted letters.
The guard helped her find the library, which had a room with a standing whiteboard. Raisa briefly considered pushing it back through the hallways to the interrogation room with Kilkenny, but the sheer absurdity of that image stopped her.
Instead, she grabbed a marker and pulled up one of Conrad’s letters.
He hadn’t wanted the investigation team to actually decrypt them before the victim was dumped. He wasn’t stupid or sloppy. The whole shtick of including the name was just a power play from a sadistic asshole. But it could only be a power play if he came out on top every time.