Interesting that Jane and Kirkland have this conversation in episode 5.7 "If it Bleeds, it Leads"
Jane: "Do I know you?"
Kirkland: "No, But I know you!"...
Now, before Robert Kirkland tortures and or kills a suspect, he asks: "Have you ever seen me before? Are you positive?"
We recently learned this is because he has a twin brother. So why would Robert Kirkland answer with a quick No when Jane asks "Do I know you?"
It appears that Michael Kirkland has made some appearances on the show. He's probably still alive.