Roommate faces murder charges in deaths of 2 University of South Florida doctoral students

A 26-year-old man is facing two counts of first-degree murder in the deaths of two University of South Florida doctoral students who went missing last week, local authorities said Saturday. 

The Hillsborough County Sheriff's Office in Florida said that evidence presented to the state attorney's office resulted in the charges against Hisham Abugharbieh, the roommate of Zamil Limon, one of the doctoral students. 

Abugharbieh is accused of premediated murder with a weapon. He was arrested on Friday, the same day Limon was found dead. 

The family of Nahida Bristy, the other doctoral student, told CBS News that police said she is also likely dead. That is based on the volume of blood discovered at Abugharbieh's residence, which he shared with Limon.

"Police told us she is no longer with us," Bristy's brother, Zahid Prato, said early Saturday.

The family was told her body may never be found and police believe she may have been dismembered, according to Prato. 

CBS News has reached out to police for more information.

Authorities said in a statement Saturday they were still searching for Bristy.

Limon's remains were found on the Howard Franklin Bridge in Tampa Friday morning, Chief Deputy Joseph Maurer with the Hillsborough County Sheriff's Office said. His cause of death was pending autopsy results.

Deputies with the sheriff's office took Abugharbieh into custody on Friday after responding to a domestic violence call at a home in the Lake Forest Community, a neighborhood near USF's Tampa campus, officials said. He also faces charges including battery, false imprisonment, tampering with evidence, failure to report a death and unlawfully moving a body. 

Limon and Bristy, both 27, had last been seen in the Tampa area on April 16. 

Limon was studying the use of AI in environmental science and was set to present his doctoral thesis this week, his family said. Bristy is studying chemical engineering.