"This is where my mom was murdered." So states Beckett in the preview above, which is for the major episode "Knockdown."
Added:

Castle Season 3 Episode 13 Quotes

It's different when it happens right in front of you.

Beckett

Raglan: What part of no cops don't you understand?
Beckett: He's not a cop.
Raglan: Than who is he then?
Beckett: Just someone I trust.