and back in may of 2012, did you know a lisa techel? before lisa married seth and ended just weeks before her murder. >> mr. tennis, at some point did your relationship with lisa techel become sexual? >> yes, it did. >> when we talk about a sexual relationship, we're not talking about texting. are we? >> no, sir. >> reporter: you're talking about actual sexual intercourse. >> yes, sir. >> reporter: for lisa's father, the revelation that his daughter had a lover was the cruelest blow yet. >> the first emotion i had was why, why, lisa, you know. and my second thought is, i don't want to tell amy because i know she's not going to be happy. >> reporter: does it taint your memory at all? >> really what it did for me more than anything is i have so many more questions that i'll never get the chance to ask her. i mean, i love lisa. and she was a human being. she made mistakes. >> reporter: the graphic testimony about lisa's affair and how police overlooked it fit perfectly with the defense's theme of a botched investigation and a rush to judgm