The medical examiner's office will determine the causes of death as the investigation continues.
The bodies of 22-year-old Rotana Farea and 16-year-old Tala Farea were discovered bound together washed up on the shores of the Hudson River in NY.
The same relatives reportedly rejected the idea that the sisters shared a weird suicide pact, though that remains cops' working theory, police sources said.
Two months ago, the mother reported Tala as missing, but later withdrew the report after the teenager was found visiting her sister in NY.
The younger sister, Tala, had been reported missing on August 24, according to the National Center for Missing and Exploited Children.
The women's bodies washed ashore off of Manhattan's Upper West Side on October 24, bound together with duct tape, police said.
Police told the New York Post that they believed the women had entered the river from the George Washington Bridge and then floated more than 100 blocks south to just below Riverside Park, which stretches for 50 blocks along Manhattan's west side. There were no obvious signs of trauma, police said.
The family members on October 28 also denied that the sisters were missing since August, noting that their mother initially did report Tala missing but soon found that she had been visiting her sister in New York City.
The bodies of the two women that were bound together by duct tape washed up from New York's Hudson River on Wednesday.
"They were a democratic family, they never had any issues and the eldest was sent to college in New York City with her family's blessing", said the family member.
Arab News reported that both sisters were in touch with their mother until about a week ago.
The Hudson River separates NY from New Jersey, and police were scouring the river banks to see if they can establish where the sisters entered the water.
The sisters were found laying on rocks near the river, fully-clothed, both wearing black jackets with fur trim and black leggings.