. >> reporter: john kruger was born in napa. like his daughter sara. now accused of leaving kayleigh's lifeless body behind. >> i cannot believe she would leave kayleigh there like that. it's beyond words. >> reporter: manipulated, kruger says by the man he blames for the killing. sara's boyfriend, 26-year-old ryan warner. >> there's a monster that started all of this. i can say 10 months ago, when he came into my daughter's life, it's been, she has been a changed person. >> reporter: her father noticed what neighbors and friends also saw. sara, much thinner, rarely outside, signs of methamphetamine use. >> the sara that i know and love, used to call her dad every day. >> reporter: over time, calls dwindled, and communication became strained. >> she knew i didn't approve of her boyfriend. >> reporter: kruger last spoke to his daughter three weeks ago. he knows people will judge her harshly. >> we need to not focus so much on sara. this is more about kayleigh, than anything else. this is about a little girl who's life was ended way before it was time. >