Castle's partner

A hint

Her body stiffens and her face turns to stone.
"Are you sure?"
"Yes he was a suspect in the file! Beckett this could be my only chance to get him to tell me who killed my dad. Make a deal with him! If he tells you what he knows about my dads case his sentence for whatever he did this time gets lessened!"
She looks exasperated.
"Ill try. I don't know if he will though!"
"I'm coming in with you."
"What? No you can't do that. You haven't been in before you don't know how to do this."
"Hell yeah I do. I've been watching the best detectives in New York for almost a year, I think I can do this."
"No, I'm not letting you. It's dangerous."
"Beckett come in! You know what's dangerous? Not knowing who killed my family! Look what they are capable of, murder, kidnapping, torture. Without them in jail I'm always in danger!"
She opens her mouth to argue, but quickly shuts it again realizing my words ring with truth.
"Fine, but you have to follow my lead."
I pick up my dads file and follow her into the box. The man is sitting down, rubbing the back of his head.
He sees me, and a look of panic crosses his face.
"Who the hell are you?"
I sit across from him with Beckett.
"Do you know who this man is?" I pull out a picture of my father. His finger twitches before he all too quickly answers, "No. And what does this have to do with anything anyways?"
"Tell us everything you know about his murder, and his children, and I will tell the D. A. You cooperated."
He studies his fingers, and then again the picture.
"Ok. Maybe he does look a little familiar. But I swear I didn't kill him! Or his kids!"
My anger swells again, and Beckett holds my wrist.
I pull away from her and continue.
"Who killed him?"
He looks pained, as though he is debating telling me or not.
I slam my hand on the table, breaking the silence.
My voice comes out tight, serious and low.
"You best tell me. I don't think you want to find out what will happen to you if you don't."
I feel Beckett's hand on my leg, subtlety telling me I need to calm down.
The man across the table opens his mouth.
"Ok fine. From what I hear, this man found out some stuff he shouldn't have, and his kids too. He found out something that could have seriously damaged some people's reputations, and he didnt even mean to. They killed him and his family after his wife died."
"Who?" I repeat my question.
"Who? I think you have figured it out by now." He looks at me.
I knit my eyebrows, wondering what he is talking about. Then it hits me.
"Jerry Tyson." I mumble.
Beckett jerks next to me.
"I'm sorry, did you just say Jerry Tyson?" Her face goes pale, like she saw a ghost.
I stand up and walk out of the room, and Beckett follows.
"How the hell is Jerry Tyson connected to your fathers murder?"
"My dad was an accountant. One day he came across a check that was for over a million dollars, so by law he had to make sure everything was legal. He did, and everything was fine except for one thing. It was traced to an account that was routed through Africa first. It was eventually traced to Jerry Tyson. He was questioned as to why he had the money and his answer was a relative in Africa died and gave him money, and the police bought it. But my dad wasn't convinced. He said he stopped caring about it but what if he didnt? What if that's why he was killed? He figured out what was going on and then- then he was killed. And my siblings."
She looks at me as if in pain.
"Ross, I don't know if we will ever catch this guy. He's a serial killer. At least 60 cases were because of him."
"We have to. I will catch him, even if I die doing it."