>> there's that son of a bitch, jack despain. >> reporter: did you think jack was somehow responsibleh, yeah. marc had told multiple people, if anything ever happens to me, y'all look at my dad. >> reporter: so, of course, detective brooks invited jack down to the police station. just maybe this mystery would have a quick, if very disturbing, solution. >>> coming up -- a young girl makes a troubling accusation that defines a fy. happened? >> but was that the motive for murder? was it even true? when "dateline" continues. z2ejdz z16fz y2ejdy y16fy >> reporter: it's an unpleasant thing to think about. parents murdering their own children. but it happens. it's an old story, frankly. some awful glitch, perhaps, in the human recipe. had it happened here, in jonesboro? suspicion fell quickly on marc's dad, jack despain. michelle's mom heard about it when she called to tell a relative that marc was dead. >> somebody's murdered marc. and he was like, "oh my god." he said, "have they found jack despain?" >> reporter: he thought right away it was jack. >> uh-huh. >> reporter: because anyone clo

>> there's that son of a bitch, jack despain. >> reporter: did you think jack was somehow responsibleh, yeah. marc had told multiple people, if anything ever happens to me, y'all look at my dad. >> reporter: so, of course, detective brooks invited jack down to the police station. just maybe this mystery would have a quick, if very disturbing, solution. >>> coming up -- a young girl makes a troubling accusation that defines a family. >> oh, my god. could this have possibly happened? >> but was that the motive for murder? was it even true? when "dateline" continues. and i'm an arborist with i'pg&e in the sierras. the drought in california has killed trees on a massive scale. any of those trees that fail into power lines could cause a wildfire or a power outage. public safety is the main goal of our program. that's why we're out removing these hundreds of thousands of hazard trees. having tools and technology gives us a huge edge to identify hazard trees. my hope is that the work we're performing allows that these forests can be sustained and enjoyed by the community in the future. toget