The remains of one of the two missing University of South Florida doctoral students were discovered by investigators Friday and his roommate was taken into custody, authorities said. Joseph Maurer, of the Hillsborough County Sheriff's Office, told reporters that investigators found the remains of Zamil Limon on the Howard Frankland Bridge in Tampa Friday morning. In these photos released by the University of South Florida Police Department, Zamil Limon and Nahida Bristy are shown. University of South Florida Police Department Investigators have been searching for Limon and fellow USF doctoral student Nahida Bristy since they went missing on April 16. "We are still actively searching for Nahida," he told reporters during a news conference Friday. Maurer said investigators received a 911 call for a domestic violence disturbance around 9 a.m. Friday at a residence where Limon's roommate, Hisham Abugharbieh, had barricaded himself.…