The last person to see Pitt student Sudiksha Konanki alive on a Dominican Republic beach was a 24-year-old tourist from Iowa, who fled the rough surf but left her behind — then passed out drunk on the beach, according to local reports.

Joshua Steven Riibe, a fellow guest at the Caribbean resort from tiny Rock Rapids, told police Konanki was nowhere to be seen when he woke up from his stupor, Dominican news outlet El Nacional reported, citing authorities.

Now, officials are trying to piece together her last moments as a massive, four-day search continues.

The 20-year-old co-ed was on spring break with five friends at the Riu Republic Resort in Punta Cana on March 6 when she went missing, El Nacional reported.

One of the missing student’s travel companions told authorities that she saw her on the beach around 5:50 a.m.

According to the Dominican media outlet Noticias SIN, surveillance cameras caught Konanki and her friends partying at a disco at the upscale resort around 3 a.m. 

Around 4 a.m., the group was seen leaving and heading out to the beach and stayed there until 5:50 a.m., when they left Konanki and Riibe alone on the beach.

Noticias SIN reported that Riibe has given three versions of what happened next, first telling police he threw up from the rough surf and went back to shore — but asked Konanki if she was OK.

In the second version, he allegedly said he felt sick to his stomach and left the water, last seeing the missing woman in knee-deep surf before passing out.

Finally, he also told authorities that he saw Konanki walking along the shore before he fell asleep, the outlet said. 

Police have not said if they suspect foul play but said Riibe is cooperating with authorities. 

Riibe’s father declined to comment on Monday.

“I don’t know that we’re allowed to comment at this time,” he told The Post during a telephone call. 

Konanki’s disappearance sparked a massive search of the area and the waters off the resort, with choppers, drones, boats, scuba divers and four-wheel all-terrain vehicles deployed. 

Given the amount of time she’s been missing, the chances of finding her alive are “minimal,” Juan Salas, director of the Dominican Republic’s civil defense, told Listin Diario.

Police believe the pre-med student likely drowned after jumping into the ocean in a brown bikini, with some outlets reporting she left her clothes on a chaise lounge at the beach.

Her father, Subbarayudu Konanki, filed a complaint Monday seeking to expand search efforts over his “growing suspicion” that she could be the victim of kidnapping since her body never washed ashore.

“She’s not found, so we’re asking them to investigate multiple options, like kidnapping or abduction,”  he told WTOP-TV.

Officials have insisted there were no signs of foul play at the scene.

According to the complaint, Konanki’s “belongings, including personal items like her phone and wallet, were left with her friends, which is unusual because she always carried her phone with her.”

Konanki and others were spotted on surveillance footage near the beach shortly before she went missing.

Officials at the resort said her friends did not report her disappearance until 4 p.m. Thursday, roughly 12 hours after she was last seen.

A search for Konanki was still underway on Monday, with boats and aircraft scouring the sea and ATVs combing the beach.

An Indian national from Chantilly, Virginia, she is described in missing posters as 5 feet 3 with black hair and brown eyes.

Konanki was staying at the resort with five other female students from Pitt, according to the sheriff’s office in Loudoun County, Virginia, where she is from.

Agencies from Loudoun County, along with the Indian Embassy in the Dominican Republic, have been assisting with the search. US federal agencies are also helping with the investigation.