Disclaimer: I do not own Numb3rs or the characters. No copyright infringement is intended.

A/N: Thank you, everyone, for the reviews. They've been quite helpful and interesting! And I appreciate them all!

I offer my grateful thanks to rhiannondavidson for agreeing to beta these chapters. She was nice enough to point out a typo in an earlier chapter and you know what they say: No good deed goes unpunished. Thank you, Rhiannon!

Chapter 4

Charlie slumped back in his chair with a sigh as he realized he'd lost his place in the file he was reading for a third time. He'd been sitting in his office sifting through personnel files for hours and they were all starting to run together. Normally, the FBI did most of the research and just gave him the raw numbers to plug into his equations. But in this case, Charlie thought it best to do the work himself since it was FBI employees that he was investigating.

Don was convinced the leak was a new hire or recent transfer. However, game theory suggested that a more entrenched, trusted member of the team would have a lower risk of discovery and a higher chance of gaining access to sensitive information. He suspected Don simply preferred to think the leak indicated a flaw in the hiring process rather than a betrayal by a trusted member of his team.

Director Merrick had approved the investigation and the agents had all signed waivers as part of the hiring process agreeing to periodic background checks. Still, accessing personal information such as performance reviews and credit reports really brought home to Charlie how much trust Don regularly extended to him and he vowed to be more diligent in his discretion.

Just as he was about to pick up the file again, Larry appeared in the doorway. Charlie waived him into the office eagerly, happy to have an excuse to put the work aside for a moment.

"Hello, Charles," Larry greeted. "What new intellectual pursuit has captured your imagination?"

Charlie closed his laptop and leaned forward, crossing his elbows on top of the open file in front of him in a move that he hoped seemed casual. "What, ah, what makes you think I'm working on something new?"

Larry raised his eyebrow and replied in a bemused tone, "Well, I assume something kept you from attending Dr. Endel's lecture today." Pointing to himself he added, "Even I, a mere theoretical physicist, recognized the unique opportunity…"

Charlie tuned out Larry momentarily so he could concentrate on resisting the urge to bang his forehead against his desk repeatedly. Dr. Endel, a strange but brilliant mathematician, was something of a recluse. He disliked public speaking and rarely traveled to other universities. Charlie had been looking forward to attending his presentation for weeks, but he'd gotten so wrapped up in his investigation that he'd forgotten all about it.

Charlie looked up to see Larry watching him with a concerned expression. "So, what is it? Some new case for Don?"

"Ah, n-no, it's… I mean, I'm not…" With a sigh, Charlie abandoned his stumbling evasions and admitted, "I really can't discuss it."

Larry chuckled as he sank into the visitor's chair across the desk from him. "Charles, I'm well aware that you occasionally work on classified projects. I've never taken offense before when there was something you couldn't tell me. Therefore, logic would suggest there's no reason to expect a different reaction from me now."

"Thank you, Larry. I see your point. It's just that…" Charlie lowered his voice and confided, "Don thinks someone in his office is leaking information to the media. About the Gutierrez case. That woman who was murdered a few days ago…"

Larry nodded in recognition and screwed up his face in disgust over the vicious nature of the crime. "Yes. I've seen reports about it on the news."

Tapping the file in front of him, Charlie explained, "I'm looking into all the agents who've had access to the case, trying to determine which of them have the highest probability of passing or selling information to the media."

"But aren't you making a false assumption?"

Charlie tilted his head, intrigued by Larry's challenge and eager to hear any insight he had. "How so?"

Larry rubbed a hand over the back of his neck as he explained, "Well, I mean it's more than the FBI that you have to look at isn't it?"

Charlie nodded. "Yes, Don thinks it may be someone an agent is talking to in confidence who's passing the information on to a reporter."

Larry pressed his fingers together in a thoughtful gesture. "Well… Yes, that's certainly possible. But, actually, what I was thinking of was all the other people who might have inside information about the crime." He began ticking off examples on his fingers. "Employees of the coroner's office, the unfortunate individual who discovered the body, the police officers who first arrived on the scene…"

Charlie leaned back in his chair, realizing that his list of suspects had just grown quite a bit. "I see what you mean."

"Well, I'm afraid I've made your load heavier instead of lighter. Can I make amends by offering my help with your research?"

Charlie hesitated, sincerely tempted by the offer, but then shook his head. "No. I'd prefer to work on this on my own. It's not that I don't…"

Larry waved off the explanation as he stood up and started toward the door. "Don't apologize. No offense taken. The files you're reviewing no doubt contain some very personal information. I'm sure Agent Reeves and the others appreciate your discretion." As he reached the door, he turned and paused to survey the tall stacks of files piled on Charlie's desk. "Well… good luck, Charles."

As soon as Larry walked out the door, Charlie almost called him back. Instead, he took a deep cleansing breath and went back to reading the file in front of him.