The sisters, who were seen roughly between 158th and 163rd Streets, were seated several feet from the river, which could explain why they were found downriver, Chief Shea said.

At about 3 p.m. that day, a passer-by discovered their bodies, clad in similar black jackets and black leggings, below a pier about 100 blocks south near 68th Street. Their bodies were wrapped in tape, which was “keeping them together,” but it was not tightly binding them, Chief Shea said.

“It is entirely credible that the girls entered the water alive,” Chief Shea said. “We have them praying a short distance from the water. We also have sources that detectives have developed thus far, statements that they would rather inflict harm on themselves, commit suicide, than return to Saudi Arabia.”

The Farea family moved from Jeddah, a port city in Saudi Arabia, to Fairfax, Va., about three years ago. The sisters lived with their mother and at least two brothers, according to neighbors and the Arab News, an English-language Saudi Arabian newspaper. Their father traveled back and forth between the two countries, relatives told the news outlet.

Tala Farea briefly attended a public school in Fairfax County for her sophomore year, according to a spokesman for the school district, and Rotana Farea was an engineering student at George Mason University from early 2016 until last spring.

“The news of her death is tragic,” a spokesman for the university said. “University officials are cooperating with police and will assist in any way we can.”

The family was kind and cordial, said a neighbor who lived next door to the family at an apartment building in Fairfax from 2016 until they moved out in early August and who asked not to be named. He said he saw the father about three times and would typically see the mother interacting with other Muslim women who appeared to live in the building.