Federal prosecutors for Iowa say a former medical student who sold guns to a felon and tried to hire a hit man has been sentenced to more than seven years in prison. Officials say 36-year-old Steven Arce, of Waterloo, was sentenced Wednesday in Cedar Rapids to 90 months in federal prison. He pleaded guilty in March to one count of selling a firearm to a felon. With his plea, Arce admitted that he sold an AR-15 rifle to someone he knew was a felon, asking the man during the exchange if he could kill one of Arce’s medical school professors. A couple of weeks later, he sold a second gun to the same man, and Arce arranged to meet with someone he believed to be a hit man. The next day, Arce met with the hit man, who was actually an undercover officer. Officials say Arce offered a machine gun as down payment on the killing before he was arrested.