the bourdeau case faded away.a decade later, dennis got that called from reporter larry oldman about the murder of larry risken. that was the first you heard she even had another husband. >> yeah. >> did he tell you how he died? >> he told me just how he got shot in the head, too. >> just like your brother? >> yeah. yeah. >> did you immediately think, oh, boy, she's done it again? >> yeah. i did. >> maybe now, hoped dennis, all the renewed interest in sonia might finally reignite the investigation into his brother's case. >> i thought, sonia was going to be hung from the highest tree and serve a lifetime behind bars. >> understandable, if naive. >> coming up -- >> had she been arrested, larry risken would be alive today. >> you looked at the report. >> oh yes, very sensibly. >> what other secrets might sonia be hiding? when "dateline" continues. with progressive. you saved money and you get round-the-clock protection. so don't worry. it's all under control. [ screaming continues ] that's cool. we'll finish up here