The man who was detained after two Bangladeshi doctoral students went missing from the University of South Florida (USF) has been booked with two counts of murder.

Hisham Abugharbieh faces two counts of premeditated murder in the first degree with a weapon in the deaths of Zamil Limon and Nahida Bristy, the Hillsborough county sheriff’s office announced on Saturday.

Abugharbieh was the off-campus apartment roommate of Limon, whose remains were discovered on Friday morning on the Howard Frankland Bridge over Tampa Bay. Bristy remained missing as of Saturday morning – nonetheless, unspecified evidence presented to the local state attorney’s office led to Abugharbieh being booked with her murder in addition to Limon’s.

The Hillsborough county sheriff’s office said it would “not be commenting on the findings in the case” against Abugharbieh “to protect the integrity of the investigation”.

After the discovery of Limon’s remains, Abugharbieh had been arrested at his family’s home nearby on preliminary charges that included unlawfully moving a dead body, failure to report a death, tampering with evidence, false imprisonment and battery.

Officers encountered Abugharbieh as they responded to a report of domestic violence at his family’s home, just north of the campus, and were able to remove his relatives to safety. He then barricaded himself inside and refused to come out. A special tactical team responded, along with a drone, a robot and crisis negotiators, before Abugharbieh came out with his hands up, apparently wearing nothing but a blue towel.

Limon and Bristy, both 27, were a couple, and they were considering marriage, a relative said. They disappeared from the USF campus on 16 April.

Limon, who was studying geography, environmental science and policy, was last seen at his home in an apartment complex where he lived with Abugharbieh. Bristy, who was studying chemical engineering and lived on campus, was last seen an hour later at a campus science building.

A family friend contacted authorities on 17 April after being unable to contact either one, USF police said.

Investigators said they interviewed Abugharbieh, who is a US citizen, on Thursday, but Abugharbieh ended the interview. He was speaking with detectives again after his arrest on Friday.

Abugharbieh is considered the only suspect in the case, which gained national media attention after it was reported.

An autopsy was being done on Limon to determine his manner and cause of death. Results were possible by Saturday, according to investigators.

“This is a deeply disturbing case that has shaken our community and [affected] many who were hoping for a safe resolution,” the Hillsborough county sheriff, Chad Chronister, said. “While the discovery of Zamil Limon’s remains is heartbreaking, I want the public to know that our detectives worked and are working tirelessly and relentlessly to uncover the truth.”

Abugharbieh had studied at USF but was not enrolled at the time of his arrest. University records showed he had attended the school from 2021 to 2023 and had pursued a bachelor’s of science in management, a USF spokesperson said.

He had several previous arrests, the sheriff’s office said. He was charged with battery and burglary of an unoccupied dwelling in September 2023, and with battery that May, both classified in court records as misdemeanors. Court records show Abugharbieh may have entered into a diversion program.

The Associated Press reported calling his lawyer in the case, but the call was not immediately returned.

Hillsborough county court records also showed two domestic violence petitions filed by a family member in 2023. A judge granted an injunction in one case and denied the other petition.

The Associated Press contributed reporting