dr. macneill began an affair?>> yes. >> when "dateline" continues. as parents we hold our kids' hands when crossing the street so think of the internet as the world's busiest street. teach your kids to surf and post responsibly. they'll be safer with a dedicated crossing guard... the more you know. >>> what a strange thing it was, that the day martin macneill was charged with murdering his wife, his daughters' only regret was that it had taken more than five years. >> i think my dad really got off on seeing what he could get away with. >> when the trial began this past october 17th, provo, utah, martin was noticeably pale and prosecutor chad grunander was little worried. >> it seems like a case where you maybe had the impression that the guy was guilty, but proving it was not going to be an easy manner. >> it's going to be difficult to wrap it all up early and give the jury this nice little box with a bow on top. >> gypsy willis and the defendant -- >> the prosecution told the jury that martin drugged and drowned