*FBI Headquarters, White Collar Division*

It was three in the afternoon and they still had no new leads for the murders since solving the robbery case. The four of them had been sitting around a table for couple of hours now looking through files and trying to connect the dots.

Peter lets out a sigh and gets up from his chair. "Alright, who needs more coffee?" he offers.

"Me," Rick hands him his mug. Neal lifts his mug towards Peter without looking up from the file he was reading.

"Detective?" Peter asks Kate.

"No, thank you. I'm good," Kate shakes her head. Peter then heads toward the coffee machine with three mugs in his hands.

"We've been at this for hours," Neal finally speaks. "How do you guys do this?"

"We usually catch the killer before we find the loot," Rick says. "Now that it's the other way around, we're back at square one."

"We're not back at square one," Kate tells him. "Alright, so we know that the killer is definitely male and that this murder was a personal one."

"So the killer is someone Jordan knew," Rick says.

"What about the bodyguard?" Neal suggests. "Maybe the target was him and she happened to be there so he killed her too?"

"No, it can't be," Rick says. "He was shot in the head. A fast kill."

"And she took two to the abdomen," Kate adds. "The killer did not want to kill her off on the spot. He wanted her to bleed to death."

"Ugh, that's just sick," Neal cringes.

Peter walks back to the table with three cups of steaming coffee. "What did I miss?" he asks.

"We were just going through the facts," Rick answers.

"Again," Neal adds.

"Oh well then, I can add to that with these lab results I've been going through," Peter lays out a few documents on the table. "White powdery substance found at the crime scene. It's traces of cement."

"Yeah, we ruled that out earlier," Kate tells him. "Those kind are too widely used at construction sites. Found almost anywhere in the city."

"Okay, then there's the—" Peter continues.

"Wait a minute," Rick stops him. "You said cement right?"

"Yeah…" Peter says.

"But it's too commonly used to track," Kate adds.

"I was reading the suspects list we had earlier and…," Rick says as he pushes aside a few files to look for a specific one. He finds it and hands the list for the rest to see. "See the name Tyler Rees?"

"The ex-boyfriend?" Kate asks.

Rick nods his head. "Guess where he works."

"At a construction site?" Neal tries.

Rick nods his head again.

"Makes sense," Peter says. "That's how the cement traces got into the loft. He must have brought it in when he killed them." Peter signals Diana to come over to where they are.

"Diana, could you check if the construction site Tyler Rees is working at uses the same type of cement as the one found at the crime scene," Peter tells Diana.

"Alright give me a minute," she nods as she goes back to her work table.

"So he robbed and shot them," Kate comments.

"Technically, he shot then robbed them," Rick tells her. Kate shoots him a look. "He must have shot the bodyguard first in order to get in then rob the place," Rick explains.

A couple of minutes later, Diana comes back with a few documents in her hand. "We checked their accounts and the construction site orders their cement mix from the same manufacturer as the one found at the crime scene," Diana tells the four of them.

"That's it, we got our guy," Peter starts to stand up.

"Wait, I found something else that might help," Agent Jones says as he joins them. Peter sits back down.

He hands him the documents. "I did a quick background check on the guy. Turns out he was accused of several cases of domestic abuse," Jones says.

"Does one of them include Jordan?" Neal asks.

Jones nods. "Right here," Peter hands the document to the rest to see when he was done reading.

"We did a background check on him earlier and those accusations did not come up," Kate says defensively.

"Because those charges were dropped," Jones explains. "And they were very well hidden."

"But why not cover up the rest of his rap sheet too?" Rick asks. "He had a couple of counts of public misconduct."

"Well, those were pretty recent. These accusations? They go way back," Jones answers.

"So someone decided not to cover up for him anymore?" Kate ponders.

"I guess you can't count on anyone to always be there to cover for you after one too many cases," Neal comments.

"More like three too many," Rick adds.

"Okay, I'll send some guys to pick him up. He should be at work," Peter says. "Jones, get us a warrant for Tyler's place and car." Jones nods as he goes off to do what was told.

"Why don't you check out his place? The stolen paintings might be there. Castle and I will handle Tyler for the murder case," Kate suggests to Peter.

"Alright. Neal, you're with me," Peter agrees with her.

After Peter and Neal left, Rick turns to Kate. "So I was right all along then?" Rick smiles proudly.

"About what?" she raises her eyebrow.

"Jealous ex-boyfriend? I mentioned it earlier," he explains.

"It's not certain yet," Kate tells him, not wanting him to gloat.

"Oh but we are so close," he smiles.

*Interrogation room, FBI Offices*

Kate and Rick step into the room, not their usual interrogation room back at the precinct but this will do. They take their seats across their current suspect, Tyler Rees, the victim's ex-boyfriend. Kate places a file she was holding on the table.

"Hey come on, I told you guys all that I know already," Tyler says as they sat down. "If you keep taking me away from my job, I'm not gonna have one anymore."

"Oh I wouldn't worry about that," Rick tells him. "That's the least of your concerns right now."

"What are you talking about?" he asks Rick. "And who are you? I recognize her but you weren't here the last time."

"I'm Rick Castle. Consulting on the case," he answers.

"Consulting?" Tyler asks.

"Alright Tyler, quit the act," Kate interferes. "We have evidence that places you at the crime scene where your ex-girlfriend and another man were murdered."

"I don't know what you're talking about," Tyler shakes his head. "I didn't do it."

"You don't?" Kate prompts. "Then explain this," she says as she pulls out a photograph of a gun inside of a car's drawer compartment and places it in front of Tyler.

"We found this in your car," Kate adds.

"You guys went through my car?" he asks. "Do you even have a warrant?"

"As a matter of fact, we do," Kate shows him the search warrant document.

"The bullet that killed Jordan and Dominic are 9mm's which happens to be a perfect match for this gun," she points to the photograph.

"It isn't mine. Someone planted it there," Tyler tries.

"Are we really going to do this all day?" Kate sighs.

"You're going to run out of excuses soon, you know," Rick adds.

"Once the full test results come back, it's going to tell me that your fingerprints are all over it," Kate tells Tyler.

"Why did you kill her?" Rick asks.

Tyler doesn't answer.

"Didn't you say you loved her?" Rick asks again.

"I did!" Tyler replies angrily. "I do," he says softer now.

"So you shot the bodyguard and Jordan then robbed the place," Rick says, emphasizing on the word 'then' as he turned to Kate. Kate rolls her eyes in reply to him.

"Robbed?" Tyler asks, with a confused look. Again, he was trying to pretend but Kate and Rick could tell.

"Really? You want to try to lie your way here too?" Kate asks. "Cause I have people searching your place right now."

"Oh yes, that search warrant? Includes your apartment too," Rick tells him.

"You've already got murder and theft on you, you want lying to a police official too? Once my phone rings and they tell me that they've found those missing pieces, I can't help you anymore," Kate says. "You confess everything now, it won't be that hard on you."

"Alright, alright," Tyler sighs. "I didn't want to do it alright? I loved her so much and she pushed me away after she found this sonofabitch rich gallery guy."

"You abused her," Kate says.

"I might have hit her once. But I was drunk that time okay? I've been sober for months now. Since she left me, I've cleaned up. No more alcohol, even been going for AA every week now. I told her that but she said she didn't believe that I've changed. It was that rich ass who's stealing her away from me. I tried to talk to her but then he goes and hire this damn bodyguard and now I can't even see her. I went over to his place and tried to set things straight. Tell him to back off 'cause she's mine. Always been."

"With a gun?" Kate asks.

"I brought that along just to scare him. Thought it'd help," Tyler explains.

"But it got out of hand," Rick adds.

"The bodyguard wouldn't even let me talk to him. He even tried to take me to the ground. So I guess I must have taken the gun out and shot him. Then I saw her inside and she screamed at me. She was so mad; I've never seen her like that. It made me mad too and she wanted to call the cops. We struggled a bit and I… I accidentally pulled the trigger…" he trails off.

"I didn't mean to! I love her alright," Tyler says defensively.

"And you didn't think to call for help?" Kate asks.

"Look, if I called for help, you guys would have taken me in right away."

"It doesn't differ much from now," Rick tells him. "Why did you take the paintings?"

"I read the news. I heard that the sonofabitch and another gallery were rivals. I thought if I made the place look like a robbery then I could lead you guys towards them," Tyler says.

"Funny, you almost had it. Almost," Rick adds.

As Kate and Rick walk down the stairs to the main office area, Peter and Neal arrived. Behind them were five other feds, each carrying the missing paintings in.

"Ah, I see you found the loot!" Rick greets them.

"Indeed," Neal smiles.

"He didn't even try to hide it. Just sitting there in the apartment," Peter says, smiling as he had closed yet another case.

"Well, we have luck over on this side too," Kate smiles back at them. "The ex-boyfriend finally gave a full confession."

"So case closed?" Neal asks.

"Case closed," Kate nods back at Neal.

"Can I please see those paintings? If they're so valuable, I want to check them out," Rick pleads to Peter.

"Yeah…" Peter shrugs.

"Come on, I'll show you," Neal offers and they leave the room.

"But don't touch anything!" Peter warns them before they were out of sight.

Peter turns back to Kate. "Well, detective, it was a pleasure to work with you," he says as he extends his hand out for a shake.

Kate shook his hand. "The pleasure's all mine," she smiles. "Thank you for your help on the case."

"Thank you for letting us in on the case and getting some art thieves off the streets," he nods. "If you ever need any help on cases like these, you can call us anytime," he offers.

"And if you need help with homicide cases, happy to return the favour," Kate says. "Alright, I need to get our killer back to the precinct."

"And I need to get these paintings back to Harper."

They both nod their goodbyes and head off in different directions. Peter went up to his office and Kate went looking for Rick to head back to the precinct.

The End

A/N: Aaaand that's it. I hope all you readers enjoyed this story. I tried to get as much out of the four of them as I could because this is how I'd imagine a crossover episode of Castle and White Collar would be like, how the NYPD and FBI would assist each other in a case that involves both homicide and art theft. And of course, making Rick and Neal old friends was just something I wanted to happen.

If you liked it, do leave me review on the overall story. If you don't, you can let me know why and how I can improve.

Thank you! =)