As Mokuba Kaiba led her and Morgan into the room that served as the tournament's center of operations, Garcia gasped at the sight of the top of the line Kaiba Corp. tech that had been set up in the room.

Giant monitors had been mounted on nearly every wall, each one displaying different sets of data. The largest screen was at the far wall, showing a digital map of San Diego's Gaslamp Quarter and surrounding areas. Smaller stations were scattered throughout the room, each one manned by Kaiba Corp. employees.

"Wow," Garcia breathed. "My office at Quantico has nothing on this." She gasped, hurrying over to one of the computer stations, ignoring the irritated glare of the tech running it. "Is this the Kaiba Corp. Talon 5 with the KC Dragon B-3000 processor?" She ran her hands reverently over the tower. "I've been wanting one for ages, but the BAU doesn't have the budget."

Mokuba smirked. "You really do know your tech, huh? Though you're a little bit off; everything here is running on our latest generation of processors: the KC Dragon B-4500. It won't even be available for consumers until the end of the year."

"And I'll get to see these babies in action right now," Garcia said. "Morgan?"

"Yeah, Baby Girl?" Morgan replied, arms full of the equipment that he had offered to carry for Garcia.

"Remember how I said on the plane that Seto Kaiba is a coding god?"

"Why do I get the feeling that I'm not gonna like where this is going?" Morgan remarked.

"Oh, hush, you," Garcia teased. "I'm just saying that after this, I just might build an alter to his technological prowess."

"Are you leaving me for a younger man?" Morgan joked.

"Never, my chocolate thunder hunk," Garcia replied, "but there's nothing wrong with a girl having a completely platonic tech crush on one of the greatest minds of the century."

"You do know my brother is only seventeen, right?" Mokuba asked.

Garcia froze, having forgotten about the younger Kaiba's presence during her usual banter with Morgan. With a look of horror on her face, she mouthed, "Oh my god," at the aforementioned agent.

Morgan, amused by the situation Garcia had stumbled her way into, just chuckled. "Don't worry about it, kid," he told Mokuba. "Garcia doesn't mean anything by it. Though we should probably get back on track before we're both accused of corruption of a minor."

"I'm not a kid," Mokuba protested. "And between growing up a Kaiba and having to deal with duelists all the time, I really don't think you two can corrupt me any further." He took a quick look around. "I guess I should probably get you set up."

He led them to the control panel for the wall monitors, showing Garcia where she could hook in her equipment, before excusing himself to answer his cell.

"Moshi moshi."

"Mokuba, have the FBI arrived yet?"

"Yeah, they're here. The leader wasn't pleased that you weren't there to meet them, though."

"Too bad. Where are they now?"

"Most of them are setting up interviews in one of the conference rooms. Garcia-san and one of the other agents, Morgan-san, are setting up here in Operations." Mokuba smirked, watching Garcia teasingly boss around Morgan as he helped her connect cables and set up equipment. "You know, Nii-san, you have quite the admirer in Garcia-san." His smirk grew wider as his brother sighed, practically hearing Seto's exasperated expression at his little brother's words.

"At least try to stay out of trouble. I'm on my way to talk to Agent Hotchner and his people." Seto's voice grew softer. "Please stay safe, Mokuba."

This was a side of Seto Kaiba that few ever got to see, a side that Mokuba had once believed to have been lost to Gozaburo's hate and torture. Once more, Mokuba said a silent 'thank you' to the other Yugi for bringing his brother back to him.

"I will, Seto," Mokuba promised. "Besides, between my bodyguards and the FBI agents, I'm probably the safest one here!"

"Heh, you're probably right," Seto agreed. "I'll call you again later, if I don't see you before then."

"You better. Bye, Nii-san."

"Bye, Mokuba."

The called ended, and Mokuba pocketed his phone as he watched Garcia start up her laptop, Morgan leaning against the control panel, arms crossed, as the two continued their teasing banter. It was time to get down to business.

"So, what do you need access too?" he asked as he signed into a nearby terminal using his personal administrator access code.

"Right now, I need the tournament roster," Garcia said. "I'm gonna run background checks to try and find red flags, and start to narrow down our suspect list."

"Did you think that KaibaCorp doesn't do background checks on our duelists?" Mokuba asked. "Because we do, you know. We wouldn't have let someone into the tournament who didn't pass." He transferred the files anyways. He remembered Seto's fierce glee, normally only seen in the dueling arena, as he had to use every trick he knew to keep her out of their mainframe.

Mokuba wasn't Seto, and he didn't relish the thought of trying to keep the Black Queen out of their servers when she had already been invited halfway into their systems. No wonder Seto had been disappointed to find out that the FBI had recruited her before he had managed to take control of KaibaCorp. It was better to just give her the files she wanted rather then having Garcia go looking herself and finding out things they didn't want her to know.

"Sweetie," Garcia replied, "your brother may be an undeniable genius, but I don't think he has ever had to track a serial killer before." For the first time since Mokuba had met her, Garcia's expression was completely serious, eyes focused on her screens as pictures and names appeared and disappeared, her laptop already running whatever specialized programs she had designed for her job.

Agent Morgan, who had been watching the largest screen, suddenly spoke up. "What's with the red dots on this map, here?"

"Those? Those are the Duel Discs registered to the competitors," answered Mokuba. A number of the dots were scattered around the Gaslamp Quarter, either moving around or sitting still, with the majority all gathered at the convention center. "Here, see?" Mokuba selected one of the dots, prompting a window to pop up, displaying a picture, name, age, country of origin, and deck archetype.

"So each of those dots represents a duelist's position," Morgan stated. "Is this in real-time?"

"Yeah."

"What about the nights of the murders?" Morgan asked. "Were they recorded?"

"The system has an automatic 24-hour buffer," Mokuba said. "After the first body was found, we started to record 24/7."

"Can you bring up the recording for around the time of last night's murder?" asked Morgan.

"I think I know what you're looking for," Mokuba replied, bringing up the file for the previous night. "We thought the same thing, too. Problem is, well, you'll see."

The image on the screen changed. Rather than mostly gathered in one area with a handful of outliers, red dots were scattered throughout the map. Some were paired off, indicating duelists in battle. Others moved around the map, those duelists looking to gain an edge on sleeping competitors. The majority of dots formed various clusters, individual dots sometimes overlapping, where duelists had gone back to their hotel rooms to sleep.

"Where's Brian Donally?," Morgan asked.

"Ah…here." One of the wandering dots was soon joined by a window with Donally's picture and information. The dot paused for a few minutes before turning down an alley. Halfway down it stopped again, and the time stamp in the corner of the screen started to rapidly advance as Mokuba fast-forwarded the recording.

He resumed normal playback as another dot approached the alley. Another window popped up, identifying the dot as Grizzly Kuma, as the red dot turned into the alleyway. Before it reached Donnally's dot, it stopped and started flashing.

"That's when Grizzly Kuma found the body," Mokuba explained. "The flashing is her hitting the Emergency Services button."

"Wait," Morgan said. "I thought he died right after his duel. Where's his opponent?"

"And that's our main obstacle to catching this guy," stated Mokuba. "We know Donally-san was dueling someone who had a Duel Disc, because they're only programmed to operate against another Duel Disc. But every tournament issued Disc is accounted for, even the ones from defeated Duelists.

"We even changed the parameters to look for older models." The recording reversed by a few minutes, before all the red dots disappeared, leaving less than a handful of grey dots on the screen. "That's those grey dots, there," Mokuba said. "The only way someone could avoid us tracking them this way is if they had entirely removed or disabled an older Duel Disc's GPS tracker."

"How hard would it be for someone to do that?" Morgan asked.

"Not very," Mokuba admitted, rubbing the back of his head. "We use a special part to open them up, but someone with the right tools and know-how could probably open one up and take out the GPS."

"What about the victims' Duel Discs?" Garcia asked. "Could they have recorded the duel's?"

Mokuba frowned. "Sort of. A Duel Disc's memory only stores the last six duels, and only its own side."

"Can we see Donnally's duel," and Garcia. "Maybe there's something that got overlooked before."

"Yeah, sure," Mokuba agreed. "Let me plug it in."

"Ok, so here's Donally's last duel," Garcia explained once the Disc was plug in. "Now, let's bring it up and sync it to the GPS recording." An overlay came up on the big screen, showing one side of a standard Duel Monsters field.

The time stamp at the corner of the screen started going forward again, and Donally's side of his last duel played out before them at double time. Monsters were summoned, traps were laid, and spells were played as they watched.

"So, what exactly are we looking for?" Morgan asked, his arms crossed.

"We'll know it when we see it," Garcia answered, eyes intent on the screen. "Wait. What just-." She backed the recording up, replaying the last turn at normal speed.

Donally had managed to summon a high level monster the previous turn, obviously setting up for a possibly duel-deciding play his next turn. Only now, that monster was suddenly gone.

"Alright, mini-Kaiba," Garcia said, pausing the duel, "do you see what I see?"

Mokuba frowned, leaning closer towards the screen. "His monster is gone. His life points didn't change, so it wasn't battle damage, and his other cards are untouched. A spell card or monster effect?"

"If I'm reading the data right, it was tributed," Garcia said, watching the duel script running in another window in the smaller screen in front of her as she replayed the turn again.

"And why would that be unusual?" Morgan asked.

"Because it was his opponent's turn, and it wasn't used to summon a monster on his side," Mokuba explained. "That means that his opponent used it to summon one of their own monsters, which isn't common."

"That's it!" Garcia exclaimed. "That's how we can find our Unsub!"

"What you got, Baby Girl?"

"OK, so, while a lot of duelists use a lot of the same cards, no two decks are exactly alike, even if they prefer the same archetype," Garcia explained. "If we could figure out a way to match what we see from Donally's side of the duel with possible card effects-"

"Then we can come up with a potential deck and match it against known decks!" Mokuba finished.

"We just need a card database and a program to match effects to potential cards," said Garcia.

"We can use DuelPro," Mokuba said. "KaibaCorp collaborated with Industrial Illusions to create it, and its database is updated whenever new cards are released. It's the most complete and up-to-date card database out there."

"Then all we have to do is write a program that will allow us to run the metadata from Donally's Duel Disc through DuelPro's dueling algorithms to get us as many card matches as possible." Garcia sighed. "I hate to admit this, but I'm going to need your brother's help."

"Baby Girl, I don't think-" Morgan started to protest.

Garcia cut him off. "I'm sorry, Morgan, but while I may be the Supreme Mistress of Information, I'm not familiar enough with Duel Monsters or DuelPro to set up the sort of program we need before this guy strikes again.

"Seto Kaiba already knows the DuelPro code, and he practically lives and breathes Duel Monsters. Morgan, please," Garcia pleaded, "I need him here."

Morgan sighed and shook his head, taking out his phone. "Fine, I'll call Hotch. He and JJ are supposed to be meeting with Kaiba right now." He quickly dialed Hotchner's number.

In another conference room in the convention center, Aaron Hotchner found himself starring down a Kaiba for the second time that day. Seto Kaiba was a tall Japanese teenager with an icy glare that his brother had obviously inherited, and a stubborn dedication to the game of Duel Monsters.

Said stubborn dedication was the reason for their current standoff. Despite the clear and present danger to the duelists, Kaiba refused to cancel the tournament. He insisted that there was no reason to end Battle City so early when the situation was obviously going to soon be resolved. Hotchner couldn't be sure, what with the sardonic edge to Kaiba's words, if the young man was being sarcastic or not.

The sudden ringing of Hotchner's phone ended the standoff as Hotch answered with a brisk, "Agent Hotchner." He listened to Morgan as the other agent explained the situation, and glanced at Kaiba as he replied to Morgan with a, "Yes, he's here." A few moments later, he answered with, "Very well."

Hotchner held out his phone to Kaiba. "One of my agents needs to talk to you," he said.

Kaiba's countenance didn't change, but he took the offered phone. "Yes?"

"Mr. Kaiba? This is SSA Derek Morgan. Our Technical Analyst, Penelope Garcia, and your brother have come up with a way to possibly narrow down our suspect list, but Garcia needs your skill and knowledge in Duel Monsters and the DuelPro code. They think that they can use your help to match effects to possible cards using DuelPro."

In the background, Kaiba could hear Mokuba shouting loud enough to be heard over the phone. "Nii-sama, you have to meet Garcia-san. She's so cool!"

Kaiba closed his eyes and resisted the urge to sign. For all that Seto loved his brother, Mokuba often tried his patience. Still, he had been wanting to meet Penelope Garcia, and the challenge that Agent Morgan had given was intriguing. It wasn't so simple as merely reversing the algorithm that DuelPro used to apply a card's effects in a duel. A special program would need to be written that would search the card database for a possible cards and car combinations that would create the known end affect of each turn and standby phase.

"Fine, I'll help," Kaiba said. "The sooner this madman is found, the sooner you federal agents are out of my hair and I can concentrate on winning this tournament. I'll be on my way shortly." He indulged in a but of pettiness and hung up before Agent Morgan could reply.

"I assume you already know the situation, Agent Hotchner," Kaiba remarked as he handed the phone back to Hotch.

"I do," Hotch replied, pocketing his phone. "Garcia doesn't often ask for help."

"And I don't often give it," Kaiba said, "but her skill is of some renown in certain circles. It is quite the opportunity to see her in person. Now, if you'll excuse me?" Not bothering to wait for an answer, he left, trench coat flaring dramatically behind him as Hotchner watched him go.