reporter: and who was jerry jaocbs sister? well, becky sears. kay s best friend and neighbor. i think my jaw dropped right then. wasn t expecting that. he dropped a bombshell. reporter: becky s brother said he knew all about the affair between his sister and david. he told the investigator becky had once confided in him that david was trying to end it. she d come and meet one day or there in the parking lot crying. and i was like, you know, what s wrong? and that s whenever she told me she was having the affair. he then goes on to say that becky was, had been pretty upset, crying because david won t leave kay. he wont leave his wife to be with her. reporter: jacobs then revealed his sister had no intention of giving up on david or letting him stay married to kay. she had asked me if i knew of anyone or if i knew a way that we could do this to kill kay and make it look like an accident,
and that s when he said he beat the [ bleep ] out of her. and i said, christopher, please tell me that she is okay. please tell me that you did not do this. and what did he say? he said, i beat the [ bleep ] out of her. she s giving up her son as a killer here. she s she s throwin him under the bus. this is extraordinary. it is. do you realize how extraordinary it is as you re takin the story down? oh yes. she s groomed him as her little killer. most definitely. he was he was her little monster. i messed up because i made christopher think that i wanted him to do somethin that was horrible, when i didn t want him to hurt anybody and i made him think that i did. becky, becky, becky. and he was convinced that he was helpin me. reporter: becky told investigators that chris got rid of his bloody clothes, stuffed them in his backpack. and she drove him back to her office. and then they later showed up together at the crime scene, pretending to know no
never once has there been any kind of insinuation, not even insinuating, that i would ever want anything to happen to her. reporter: as for those repeated calls from california the morning of the murder, david insisted he was genuinely concerned about kay. is it normal for you to call her that early in the morning, call kay, you know, 7:00 in the morning? always. i always call her cause i, like, talked to derek before he went to school. i started gettin worried. i thought maybe she was in an accident or somethin out on columbia road or somethin . reporter: edmunds started thinking david was telling the truth. so he changed course and asked david whether he thought becky had it in her to mastermind kay s murder. deep down inside, do you think she could do this? i thought never. i never thought that she would be like orchestrator or set something up like this. i did not think that. desperate people do desperate things. how, see, desperate for what? she s you. you
our two vehicles. um, at her mom s house. reporter: but david insisted he d decided to end the affair. he told becky it was over. i m like, look, this is getting too close. i don t want kay to find out. i m, you know, i m done with it. you know, i m done with it. you know, i m done with- done seein each other. reporter: at least, that is, until his young son derek went off to college. i ve told her multiple times that i did not, you know, want the situation to change at home. because of derek? right. reporter: right after david called it quits one month before the murder becky decided to confess to her husband tony sending aftershocks across the lawn to kay s house. she told tony everything? yes. and tony picked up the phone and called kay? yes. reporter: the secret was out. i know that hurt her so bad and i apologized to her so much. she said she d forgive me and
to hurt my wife? kill my wife? to have my wife killed? i m not i do not believe that. reporter: edmunds kept pushing. eventually david revealed that more than once he d wondered just how desperate a housewife becky had become. he told edmunds a month before kay s murder, someone sent bizarre texts to her that hinted of the affair. david now suspected those texts came from becky. did it ever ever run across your mind at that time that maybe the text messages were comin in because your time table and becky s time table weren t the same? it crossed mind. she was trying to let kay know cause she thought that if she found out that kay would leave. reporter: david s interview went on into the night. we get up and briefly walk out of the interview. and he s still there, still being recorded and then he starts talking to himself, you know, about what have i done? oh, man. they re gonna blame me. this cannot be real. reporter: but david s interview wasn t over yet. he had