Castle, Season 2

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.