from her jail cell, has plotted another murder, and has tried to engage another inmate to murder jeffrey stern do tend to get messy, which is just what merfeld didn't want when she got in the car. >> because it would be messy in the house. >> reporter: and why not just divorce her husband? well, there was insurance money to be had if he were dead. and then, there were his feelings to consider. >> it is not that -- i was just -- it was easier than -- easier than divorcing him. you know, i didn't have to worry about the judgment of my family or about breaking his heart, stuff like this, if i get a clean getaway. >> reporter: yeah, breaking his heart, sounds like that would have killed him. >>> unbelievable. next, the war within. how an alarming number of american troops are using a dangerous synthetic drug that is shockingly easy to come by. >> abc news "nightline," brought to you by progressive. hey, buddy? oh, hey, flo. you want to see something cool? snapshot, from progressive. my insurance company told me not to talk to people like you. you always do what they tell you? no... try it, and see