What we know about the search for a University of Pittsburgh student missing in the Dominican Republic

This story originally appeared on NPR.

A person of interest has been named in the investigation of a missing 20-year-old U.S. college student who disappeared last week in the Dominican Republic while on spring break with friends.

The missing woman, Sudiksha Konanki, traveled to Punta Cana with five other people last Monday, according to the Dominican Republic’s national police force. Three days later, Konanki entered a beach area with a group at 4:15 am on Thursday near a Riu hotel, according to surveillance video. Konanki disappeared around that time, Dominican national police said.

Konanki is a resident of Loudoun County, Va., and a junior at the University of Pittsburgh studying biological sciences and chemistry on the pre-med track, the university told NPR.

Here’s what we know so far about the case:

The person of interest is also from the U.S.

Joshua Riibe, a 22-year-old from Iowa, is being named a person of interest in the case because he may have been the last person to see Konanki, said Thomas Julia, the director of media relations with the Loudoun County, Va., sheriff’s office, on Wednesday. He stressed that this is not a criminal investigation and Riibe is not a suspect.

Julia said he cannot share what Riibe has divulged to authorities, but that there have been inconsistencies among the stories shared by interviewees, including Konanki’s travel companions. They have not been publicly named, but one of them is being investigated, the Dominican national police said Sunday.

A challenge authorities are facing is that many who could be helpful to the investigation are U.S. tourists and have returned home since the disappearance, according to Julia. However, Riibe and Konanki’s friends are still being detained, he said.

Who is working on the investigation?

The U.S. Embassy alerted Dominican law enforcement of Konanki’s disappearance Friday morning, the Dominican national police said.

They also said authorities are conducting a search by land, air and water, and are using everything from drones, helicopters, divers, boats and canines, among other methods.

The University of Pittsburgh said in a statement it is cooperating with the investigation, which is also being handled by the U.S. State Department, FBI, Department of Homeland Security, Drug Enforcement Administration and Loudoun County sheriff’s office, alongside Dominican authorities.

Riu Hotels is also coordinating with authorities on the investigation.

“We would like to express our deepest sympathy to the family and friends during this incredibly difficult time,” the hotel brand said in a statement to NPR. “The safety and well-being of our guests are our highest priority, and we are fully committed to doing everything in our power to assist in this situation.”

Konanki’s parents, who have two other children in high school, returned from the Dominican Republic to the U.S. on Wednesday. Her father is hoping for “the most extensive investigation possible,” Julia said.

The Loudoun County sheriff’s office has also requested that Interpol issue a yellow notice, which is an international alert for missing persons, the department said. When a yellow notice is issued, countries can exchange information about the person, and their identity is flagged with border officials.

“There has been considerable public speculation about what may have happened to Konanki and who may be involved,” the department said Monday. “We caution anyone from drawing any unsubstantiated conclusions and are committed to ensuring that a thorough investigation is conducted before any conclusions are reached.”