I think it was possibly Peter's number and that is why Lauren is acting strained with him, but that does not mean it's him?
It's just a decoy.
Why would the number be wrote down so random? surely a detective would not just scribble it on a corner of paper and the file not be secured in a breifcase or sometihng?
nah it's bonkers, it's not Peter, Lauren is just baffled!!!