TAMPA, Fla. (AP) — Murder charges have been filed against Hisham Abugharbieh, the 26-year-old roommate of a missing doctoral student, Zamil Limon, at the University of South Florida. Authorities disclosed the charges late Saturday, revealing that the young couple, who were in a serious relationship and contemplating marriage, disappeared earlier this month.

The Hillsborough County Sheriff’s Office reported that Limon's remains were recovered from the Howard Frankland Bridge, while his girlfriend Nahida Bristy, 27, remains missing. Abugharbieh, who is a U.S. citizen and had attended USF until recently, was taken into custody after police responded to a domestic violence report at his family's home.

Upon arrest, he initially faced charges for unlawfully moving a body, failure to report a death, tampering with evidence, and battery. Abugharbieh's situation escalated when he barricaded himself in his home, prompting a SWAT team response; he eventually surrendered to authorities.

According to Sheriff’s officials, Limon was last seen at his off-campus apartment while Bristy was last spotted in a campus science building about an hour later. Families of the couple remain distraught as the investigation continues.

An autopsy is being conducted on Limon's remains to ascertain the cause and manner of death, expected to be revealed shortly. Limon studied geography and environmental science, while Bristy was pursuing a degree in chemical engineering. The search for Bristy remains ongoing.

Both students’ families urge anyone with information pertaining to Bristy's whereabouts to contact local authorities promptly.