What are the three categories of engineering models?

Worst hitman ever. - The Joe Rosebrook case centers on a long-simmering grudge, a murder-for-hire plot, and a catastrophic case of mistaken identity that went unsolved for nearly a decade. Rosebrook, a small-time Ohio fraudster and chop-shop operator with a habit of retaliating against people he believed had crossed him, sought revenge against a man named Daniel E. Ott- someone he blamed for exposing one of his earlier scams. The murder contract passed through several intermediaries until it rea