A 26-year-old man has been arrested after the remains of a doctoral student were found on a bridge in Florida, while authorities continue searching for the victim’s missing partner, officials said.

Hisham Saleh Abugharbeih was taken into custody following the discovery of the remains of Zamil Limon, 27, a doctoral student at the University of South Florida. Limon’s body was found on Friday morning on the Howard Frankland Bridge, says The Guardian.

Authorities said they are still searching for Nahida Bristy, also 27 and a doctoral student, who remains missing. “We are still actively searching for Nahida,” Hillsborough County Sheriff’s Office Chief Deputy Joseph Maurer said.

Limon and Bristy, both from Bangladesh and described as a couple considering marriage, were last seen on April 16. Limon was last seen at the off-campus apartment he shared with Abugharbeih, while Bristy was seen about an hour later at a campus science building.

Investigators said Abugharbeih, who was Limon’s roommate, is the sole suspect in the case, although he has not been charged with murder. Authorities said there are currently no other suspects.

Law enforcement officials have pointed to his proximity to Limon and the timeline of last contact as central to the investigation. They also cited his conduct during the investigation, including abruptly ending an interview with detectives on Thursday and later barricading himself inside his family’s home when officers arrived in response to a domestic violence report.

Police said officers moved relatives to safety before Abugharbeih refused to exit, prompting a standoff involving a tactical team, crisis negotiators, a drone and a robot before he surrendered. He was questioned again after his arrest on Friday.

Abugharbeih faces preliminary charges of unlawfully moving a dead body, failure to report a death, tampering with evidence, false imprisonment and battery. Authorities said the charges are directly related to the death and disappearance under investigation.

Officials also noted that Abugharbeih has prior arrests in 2023, including for battery and burglary, as well as domestic violence petitions filed by a family member that same year.

An autopsy is being conducted to determine the cause and manner of Limon’s death. Maurer said results could “perhaps” be available by Saturday morning.

Hillsborough County Sheriff Chad Chronister described the case as serious and ongoing. “This is a deeply disturbing case that has shaken our community and impacted many who were hoping for a safe resolution,” he 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,” Chronister added.

“We will continue to follow every fact, pursue every lead and use every tool available to hold those responsible fully accountable,” he said.

“Our thoughts remain with the families of Zamil Limon and Nahida Bristy during this time.”