What to know about the search for the missing University of Pittsburgh student

Investigators are searching for Sudiksha Konanki, a University of Pittsburgh student who went missing on a spring break trip with her college friends in the Dominican Republic last week.

Multiple international agencies have been searching for Konanki since she disappeared March 6 as the investigation nears its second week.

Here's what we know about the case.

Who is Sudiksha Konanki?

Konanki, 20, is a junior in biology at the University of Pittsburgh, according to the Loudoun County, Virginia, Sheriff's Office. She is an Indian citizen and permanent U.S. resident who lives with her family in Chantilly, Virginia, which is in Loudoun County.

She traveled to Punta Cana from Pitt on March 3 with five female friends for spring break, the sheriff's office said.

Konanki is in the South Asian fusion a cappella group Avaaz at college, according to the group’s Instagram account.

When was Konanki last seen?

Konanki was last seen early March 6 after she went to the beach with friends.

She disappeared after 4:15 a.m., after her friends left the beach but she stayed behind with people she met on the trip.

Security video showed Konanki and her friends entering the beach area in the Riu Republica Resort, where they were staying, Dominican Republic National Police said.

Loudoun County Sheriff Michael Chapman told NBC Washington on Monday that Konanki's friends returned to the hotel after about 40 minutes and that Konanki stayed with the others whom she met and who were not friends from college.

One of the last people who had contact with her said that "a wave hit them while they were on the beach and caused some kind of situation," Dominican President Luis Abinader said at a news conference Monday, citing local reports. Abinader said at the time that authorities were trying to piece together what happened.

Konanki's friends went on an excursion Thursday and did not realize she had disappeared until they returned, about 12 hours later, at which point they told the hotel about their missing friend, National Police spokesperson Diego Pesqueira said.

The Loudoun County Sheriff's Office was then notified of her disappearance, Chapman said.

National Police launched a search effort Friday morning, using drones, helicopters, divers, boats and canine units. The search effort was expanded Monday.

Konanki's friends were supposed to return to the United States on Friday but stayed back to aid in the search, sheriff's spokesperson Thomas Julia said.

The hotel said that beach access is always open and that security guards are stationed around the hotel and the area.

What do we know about the investigation?

Multiple agencies are involved in the investigation, which is being led by Dominican police, the Dominican attorney general's office, the FBI and a U.S. Embassy liaison. The U.S. Coast Guard is also involved.

The University of Pittsburgh said it was in contact with Konanki's family and offering support in the investigation. The Indian Embassy in the Dominican Republic is also helping in the investigation, Chapman said.

Konanki’s family traveled to Punta Cana to aid in search efforts but returned to Virginia. They declined to comment on the search.

La Altagracia Civil Defense, the local Dominican emergency operations agency, shared photos of multiple agencies searching the beach over the weekend. The hotel was also assisting in search efforts, it said.

Authorities have said it's not clear whether Konanki’s disappearance is accidental or whether foul play was involved. No signs of blood or violence were found at the beach, Pesqueira said.

National Police sent teams to monitor the beach overnight at least twice to watch how the water moves to see where a body would drift if someone drowned and to see where the waves crash.

A hotel spokesperson said red flags — which indicate "that the sea had a strong current and very high waves" — were flying when Konanki disappeared.

Dominican authorities said Thursday morning that the search was moving from the Riu Republic Resort to Macao Beach.

Officials are also looking into Konanki's phone and texts, said Chapman, the Loudoun County sheriff. She did not appear to have a history of excessive drinking, he said.

The sheriff's office said it filed for Interpol to issue a yellow notice, a worldwide police alert for a missing person, which will alert authorities if she travels to another country.

"We are going on the presumption that she’s still alive," Chapman said Monday. "We want to make sure that we're exhausting every possible lead that we can, and we feel we're doing that."

Has a person of interest been identified?

A person of interest has been identified and was interviewed at length, Julia, the sheriff's office spokesperson, told NBC News. The sheriff's office has no jurisdiction over the case but sent detectives to the island to assist local investigators.

A person of interest is "not the same thing as a suspect, as this is not a criminal matter. It is still a missing person case," Julia said.

National Police said Thursday morning that they do not use the term "person of interest" in their investigations and that no one is considered a suspect at this point.

The man, Joshua Riibe, spoke to local authorities Thursday, a sheriff's spokesperson told NBC News on Friday.

Riibe may have been the last person to see Konanki alive. He told local investigators they were on the beach "in waist-deep water, talking and kissing a little," according to a transcript of the interview that NBC News obtained.

Then, a wave crashed, sweeping them both "out to sea," Riibe said in the interview.

"I kept trying to get her to breathe, but that didn't allow me to breathe all the time, and I swallowed a lot of water," he said. He told local authorities that he used to work as a lifeguard and that he made sure to get them both back to shore.

That's when she disappeared, he said.

"The last time I saw her, I asked if she was OK. I didn't hear her answer," he said. "I looked around and didn't see anyone. I thought she'd grabbed her things and left."

According to the interview, Riibe said he was surprised to later learn that Konanki was missing.

This article was originally published on NBCNews.com