'Person of interest' in case of missing university student detained 'under irregular conditions'

An American tourist, who was the last known person to see missing Sudiksha Konanki, has been detained 'under irregular conditions' in the Dominican Republic.

The 20-year-old University of Pittsburgh student vanished on March 6 while on a spring break vacation in the Caribbean beauty spot, Punta Cana, while surveillance footage captured her heading to the beach with a group of friends - including Joshua Riibe, of Iowa - at around 4am local time.

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

Dominican police told CBS that Sudiksha, an Indian native from Virginia, stayed on the beach with one of the men as the others returned to the hotel.

Authorities have since launched a search for Sudiksha after her clothes were found on a sun bed on the Dominican Republic beach where police believe she was going for a swim, reports ABC News.

On March 13, Loudoun County Sheriff's Office named Riibe as a 'person of interest' in the case. Authorities said Riibe is not considered a suspect but 'he may have been the last one to see her'.

The 22-year-old has since been detained in his hotel room 'under irregular conditions', his family claim.

A huge search is underway for the student (Defensa Civil Dominicana)

In a statement issue to WTAE, they said: "Despite his full willingness to cooperate, Josh has been detained under irregular conditions and subjected to extensive questioning without the presence of official translators or legal counsel until Wednesday, March 12.

"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.

"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."

His parents also told CBS News they hope Konanki is 'found as soon as possible'.

Surveillance footage show the young woman walking near the beach at around 4.15am, arm-in-arm with Riibe, of Rock Rapids - located near the border or Minnesota and South Dakota.

Footage shows her walking arm-in-arm with a 'person of interest' (WTVR CBS 6)

Riibe, who hasn't been charged or accused of a crime, has allegedly given mixed accounts of what happened.

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'.

The sheriff's office previously said that there had been '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. 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 contacted the Loudoun County Sheriff's Office for further comment.