psychotherapist karen kolbe's husband answered the door. >> he came back in to get me and said, "youto get up. police are here. marshall has been found dead in the office." >> reporter: the latest victim, 72-year-old marshall levine was a counselor and life coach. he was subletting his office from karen. >> we sat down with the -- officers. and they wanted to know -- what kind of clients was he seeing, and -- you know, what was his practice like? >> reporter: because the assumption was this was about marshall. >> yeah. >> reporter: i'm wondering whether you felt more of a threat after -- the second and third murder scenes are -- are sort of announced. >> honestly, i was scared. but i also knew, or believed, that -- this was personal. and i felt in my heart of hearts that, when this shooter crossed steve off his list, that he was movin' down a list. >> reporter: if the killer did have a list, police were racing to find out why were these people on it? what did they have in common? investigators collected shell casings at karen's office and discovered they were .40 caliber. same as at