Samara eyed him warily. He'd never mentioned that much about his work before. He may have hinted about things in the past, but had never been so direct so she was surprised to hear him do so now, regardless of the game they might currently be playing underneath what they were "really" talking about.
"Okay then, we'll do it your way," she replied, not willing to argue it further. If he was as good as he said then they'd need to do it this way anyhow, because it meant finding out just what might be causing the spots to appear or even what was drawing the murderer to them.
Samara would be willing to kill someone - if that were actually necessary. He knew that, but that's not why he was asking. He was asking because he knew that she had memories of someone who was deceased thanks to her reaction earlier. He didn't know whose though and they very well could be her father's. "Eli, you know that I am willing to do - or say - anything for my family. There is no price that is too high for you or Jason."
Which was the problem here. She'd already done it and he was asking for them. Would they save their lives ultimately? She didn't know that for certain, but should she wait to find out? She decided to raise the stakes higher because he already had a clue, but it wasn't enough to give her away just yet. "I wouldn't need to kill anyone though. I already have some memories from someone who has died."