PORTLAND — Family members, friends and Harvard classmates are mourning the death of Nathan Bihlmaier, whose body was recovered from Portland Harbor on Tuesday, 2 days after he disappeared during a night in the Old Port.

An autopsy by the state medical examiner is anticipated today, but police say they have no reason to suspect anything criminal in the death of Bihlmaier, 31, an expectant father who was scheduled to graduate from Harvard Business School on Thursday.

Bihlmaier and two friends from Harvard came to the Old Port on Saturday to celebrate their pending graduation. The staff at Ri Ra Irish Pub told Bihlmaier to leave at 11:20 p.m. because he had had too much to drink, at which point he got separated from his friends, said Police Chief Michael Sauschuck.

The friends and Bihlmaier exchanged cellphone calls but could not find each other. Bihlmaier, a native of Kansas who was unfamiliar with Portland, told them he was in front of a building resembling a state capitol. Police surmise that was the U.S. Customs House, an ornate gray building on Commercial Street.

Bihlmaier told his friends he was OK. Their last phone conversation was at 12:15 a.m.

Cellphone location information shows the last known location of Bihlmaier’s phone to be in the area of the Maine State Pier at 12:54 a.m. Sunday. At that point, his cellphone went dead. Police do not know if its battery ran out or it got submerged.

The dean of Harvard Business School, Nithin Nohria, came to Portland on Tuesday to offer support to Bihlmaier’s family.

“It’s a tragic moment for our community. We’re a tight-knit school,” he said at a news conference alongside Ri Ra.

“Nathan was an outstanding member of our community,” he said. “He was highly regarded by his friends as a gregarious person.”

Nohria said graduation from Harvard Business School is a dream for many individuals and their families, and should be a time of joy, but Thursday’s celebration will be tinged with sadness.

Staff members representing U.S. Sen. Olympia Snowe, R-Maine, and U.S. Rep. Chellie Pingree, D-1st District, attended Tuesday’s news conference, after following the search for Bihlmaier closely.

Snowe was asked to be a point of contact for information by former Sens. Bill Frist, R-Tenn., and Judd Gregg, R-N.H., who have sons who were close friends of Bihlmaier and attended Harvard Business School. Harrison Frist is scheduled to graduate Thursday in Bihlmaier’s class.

Pingree also was asked to monitor the search. Her stepdaughter Carolyn Tisch Sussman will graduate from the business school Thursday, and Pingree plans to attend.

Sussman, whose father, S. Donald Sussman, is the majority share owner of The Portland Press Herald/Maine Sunday Telegram, knew Bihlmaier, although they were not close, said a spokesman for Pingree’s office.

Sauschuck said the magnitude and intensity of the search were not related to Bihlmaier’s connections.

“Whenever we have a missing-persons case, no matter what the circumstances are, we try to get to the bottom of the situation as quickly as we can, both for the individual and for the family involved,” Sauschuck said.

Eighteen officers from Portland, South Portland and the Maine State Police, wearing scuba gear, dove in the murky water around the piers and pilings of Portland’s waterfront, searching the debris-strewn bottom.

Police dragged a side-scan sonar apparatus to get a picture of the harbor bottom to help focus the search. Maine Search and Rescue used dogs that can detect the smells given off by a body under water.

Ultimately, a state police diver searching in a grid pattern made the discovery at 11:45 a.m. Tuesday in deep water off Custom House Wharf.

Police identified Bihlmaier by his clothing – a black V-neck sweater, blue pants and a gray T-shirt – which witnesses and security cameras confirmed he was wearing when he was last seen early Sunday morning in the Old Port.

Sauschuck said it would be nice if a bar followed up after telling someone to leave for being too intoxicated, to make sure they have a way to get home or have friends who can look after them.

He said the employees of Ri Ra do not appear to have committed any infractions, though police will continue to investigate the circumstances leading to Bihlmaier’s death.

Police plan to review video taken from businesses in the area to try to determine how Bihlmaier got into the water. So far, the only video they have seen that shows him is one from Ri Ra, Sauschuck said.

On Sunday afternoon, police found one of Bihlmaier’s tan Rainbow flip-flops in the water alongside Maine Wharf, just west of the Maine State Pier.

Bihlmaier’s wife, Nancy Ho Bihlmaier, his parents, Steve and Cheryl Bihlmaier, and more than a dozen classmates from Harvard Business School came to Portland as the search began. Bihlmaier’s mother told the Boston Herald that he had planned to surprise his parents at the graduation with news that Nancy is pregnant.

Brian Kenny, a spokesman for Harvard Business School who has spoken for the family during the ordeal, said, “I think we were all holding out hope he was alive.” Friends declined comment.

Sauschuck said Bihlmaier’s death does not suggest that Portland is a dangerous place.

“The city of Portland is an incredibly safe place to live,” he said. “Things do happen in the Old Port, as they do anywhere else.”

Staff Writer David Hench can be contacted at 791-6327 or at: [email protected]