both crimes. >> we were able to identify one suspect in the case and he's our prime suspect, matthew mulleruller has never been charged in either case. we wanted to hear from muller himself. his attorney did not want muller to do an interview. however, muller agreed to see a visitor. "dateline" associate producer kayla ward spent 30 minutes talking with muller in jail through glass on the phone. no cameras, no recordings, no note taking allowed. what is your initial impression of him? >> we were joking about the books he was reading. >> what's his answer as to whether or not he's guilty of the crimes he's accused of? >> he wouldn't say. he wouldn't deny anything, but he wouldn't say he was guilty of anything. >> she asked him about samantha. >> recently interviewed a woman and her case matches denise huskins and the other case. he couldn't believe that i was bringing this up. >> but he denied knowing anything about samantha's case or the one in palo alto. then kayla asked about denise huskins. >> he looked at me intensely and said can you imagine being woken up in the middle of the night, t