Castle and Lanie in “Deep in Death”

Castle

[About what he found about Beckett's mother] What was I suppose to do? Not tell her what I found?

Lanie

[Surprised] What you found?

Castle

Oh she didn't tell you, did she? Three people were killed the same way her mother was, right about the same time. One of them was a former law student of hers, another one a documents clerk, the third one a lawyer for a non-profit.

Lanie

Wait, the M.E. at the time didn't make the connection?

Castle

If he did, he buried it.

Lanie

Did you talk to him?

Castle

He died four years ago. So you see why I had to tell her.