New York (PTI): The family of missing 20-year-old Indian student Sudiksha Konanki has asked police in the Dominican Republic to declare her dead, according to US media reports.

Konanki, a citizen of India and a permanent resident of the United States, was last seen on March 6 at the Riu Republic Resort in Punta Cana town.

She has gone missing while on vacation in the Dominican Republic and US federal law enforcement agencies are working with authorities in the Caribbean country in the probe into her disappearance.

Despite an extensive search, her body has not been found.

Dominican Republic National Police spokesperson Diego Pesqueira said Konanki’s family has sent the agency a letter requesting a declaration of death, NBC News reported on Tuesday.

The Konanki family did not immediately respond to a request for comment Monday night.

Meanwhile, authorities in the Dominican Republic have confiscated the passport of the man who is the last person known to have been with Konanki, according to a source close to the investigation, CNN News reported.

Dominican Republic Attorney General Yeni Berenice Reynoso interviewed Joshua Steven Riibe, over the weekend for more than six hours and the questioning is expected to continue with a local prosecutor, the source said.

Riibe is not considered a suspect in the case and has not been accused of wrongdoing.

It’s unclear why Riibe’s passport was confiscated. Since Konanki went missing in the early hours of March 6, Riibe, a 22-year-old from Rock Rapids, Iowa, and a senior at St. Cloud State University in Minnesota, has remained under police surveillance in the Dominican Republic. He has been taken to the police station for interrogation multiple times, his parents said in a statement.

The Konanki family sent a formal letter to authorities Monday, acknowledging there is no suspected foul play involved in Konanki’s presumed death after she vanished from a Punta Cana beach in the early hours of March 6, New York Post reported.

The father and mother also wrote they trust the authorities’ probe into the case and noted Riibe, the last person to see the young woman alive, has cooperated with investigators, sources said.

Konanki's parents in the same letter said that they understand that certain legal procedures must be followed for their request, but that they are prepared to comply with any necessary formalities or documentation, sources were quoted as saying by the ABC News.

Konanki, described by her father as an “ambitious” student who planned to study medicine, arrived in Punta Cana on March 3. She travelled with five other female students from the University of Pittsburgh, according to the Loudon County Sheriff’s Office.

Riibe said he first met Konanki in the hotel when he and his friend introduced themselves to her group. The two friend groups went together to the bar, where they drank until “someone suggested we go to the beach,” Riibe said in his interview.

In the early hours of March 6, she was seen on surveillance footage drinking with five women and two men in the Riu República Hotel bar. In the video, Konanki is seen wearing a white cover-up as she hugs and talks with her friends. Riibe is seen several feet away, bent over and stumbling on the lawn outside the bar.

Then, at 4:15 am, a surveillance camera captured the group, including Konanki, entering the beach, police said.

Just before 5 am, surveillance footage shows five women and one man leaving the beach, two sources close to the investigation told CNN. Konanki was not among them.

During his fourth interview with prosecutors, on Wednesday, Riibe described a harrowing attempt to save Konanki after they were jostled by the wave and she got tired of swimming.

Authorities in the Dominican Republic have said no one is considered a suspect in Konanki's disappearance.

US authorities have said it is a missing persons case and not a criminal matter.