Murder charges have been filed against the roommate of a doctoral student from Bangladesh who disappeared with his girlfriend earlier this month from the University of South Florida, authorities said Saturday. Hisham Abugharbieh, 26, is facing two counts of murder in the first degree with a weapon (premeditated) in the deaths of Zamil Limon and Nahida Bristy, students at USF, according to the Hillsborough County Sheriff's Office. Limon’s remains were found on the Howard Frankland bridge Friday morning, but Bristy is still missing, Hillsborough County Chief Deputy Joseph Maurer said on Friday. Abugharbieh, a native-born U.S. citizen, was initially taken into custody on Friday at his family’s home on preliminary charges that include unlawfully moving a dead body, failure to report a death, tampering with evidence, false imprisonment and battery.…