Man has his 'passport confiscated' and 'is not free to leave' amid investigation into missing student

The last person believed to have seen University of Pittsburgh student Sudiksha Konaski has had his travel documents seized.

Sudiksha, 20, was last seen on March 6, captured on CCTV entering the beach at the Riu República Hotel in Punta Cana at around 4:15am with a group of friends.

However, footage recorded at around 5:55am revealed Sudiksha was not among five women and a man who left the beach.

When Sudiksha failed to return, the group she was with searched for her and when they couldn't find her, notified authorities, a police source told CNN.

A missing person report was later filed by Sudiksha's father, Subbarayudu Konanki.

On March 13, Loudoun County Sheriff's Office named Riibe as a 'person of interest' in the case, noting Riibe is not considered a suspect - nor has he been accused or charged with a crime - but 'he may have been the last one to see' Sudiksha.

Riibe was later detained in his hotel room 'under irregular conditions' and 'subjected to extensive questioning' 'without the presence of official translators or legal counsel' and 'despite his full willingness to cooperate,' his family alleged in a statement to WTAE.

"He has remained in his hotel room under police surveillance and has been repeatedly taken to the police station since March 6, where he has been interrogated for long hours," the statement continued.

"This situation has raised serious concern within his family, which has led us to retain legal counsel to initiate legal actions ensuring his safety and the protection of his rights throughout this process."

On March 14, Riibe's passport was confiscated by Dominican authorities, his attorneys told NBC News.

Sudiksha Konanki was last seen on March 6 in the Dominican Republic (Law and Crime Network)

They added Riibe is 'not free to leave'.

During a press conference on March 10, President of the Dominican Republic Luis Abinader said the last person who had contact with Konanki reported 'a wave hit them while they were on the beach and caused some kind of situation'.

However, the sheriff's office has warned about the 'considerable public speculation about what may have happened to Konanki and who may be involved'.

The news release added: "We caution anyone from drawing any unsubstantiated conclusions and are committed to ensuring that a thorough investigation is conducted before any conclusions are reached.

Sudiksha was last seen on March 6 (Facebook)

"The LCSO is hopeful for the safe return of Sudiksha Konanki, and we are committed to supporting this investigation and her family in every way possible."

UNILAD has previously contacted Loudoun County Sheriff's Office for comment.