Gianclaudio Marengo. (Courtesy of New York Police Department via AP)

It was a typical Tuesday morning for New York police officer Man Yam — hop on the commuter train in Nassau County in Long Island, hop off at Penn Station, scavenge for a seat on the downtown 2 train amid the early morning traffic. He could practically navigate the whole route without lifting his eyes from his phone, on which he reads articles from the day’s New York Daily News.

Yam was scanning a story about an Italian man who’d disappeared after crossing the finish line of the New York City Marathon on Sunday. Then his phone lost service during the transfer to the 2 train. With nothing to read, the officer lifted his eyes from the screen and looked around at his fellow passengers.

“Boom — right in front of me is the missing runner,” Yam told the Daily News. “… He had dried lips and his eyes were wandering. It was my gut feeling, ‘This is the guy.'”

The runner, 30-year-old Gianclaudio Marengo, was still dressed in the clothing he’d worn at the starting line 44 hours earlier: turquoise shirt, black shorts, a paper bib with the number “23781” emblazoned in big black lettering. The only difference was the finisher’s medal and the look of utter confusion.

According to the New York Times, Marengo had come to New York with a team of other Italian runners from San Patrignano, a center for recovering drug addicts. Antonio Boschini, who served as a medic for the Italians said that Marengo wasn’t registered for the race, but Boschini gave him his bib: number 23781.

Marengo discovered his love of running in his three years at San Patrignano, according to the Associated Press, and trained for months to get to the marathon’s starting line at the base of the Verrazano Bridge in Staten Island. At around 10:15 a.m. the starting gun went off, and Marengo and tens of thousands of other runners were on their way.

During the 26.2-mile run, Marengo reached into his bag of supplies — food, subway map, key card for the group’s hotel in Queens — to grab something to eat. The card and map must have fallen out at some point, Boschini told the Times, because when Marengo finished the race they were nowhere to be found.

It was 3:03 p.m. Marengo had run the grueling course in 4 hours, 44 minutes and 27 seconds, the Times reported. But his journey was nowhere near done.

Marengo’s Italian teammates reached out to the Italian consulate when he didn’t show up at their hotel, according to the Daily News, and the New York Police Department issued a missing person alert. Marengo was initially identified as mentally disabled, but a spokesperson for San Patrignano said that’s not true.

“He is certainly a fragile, vulnerable and very emotional person who after years of drug dependency found the chance to recover in San Patrignano,” the center said in a statement to the Associated Press. Marengo does not speak English.

Meanwhile, Marengo was wandering around New York, lost, thirsty and with his finisher’s medal still draped around his neck. He spent Sunday night in Manhattan’s Central Park, then took the subway to John F. Kennedy Airport, where his team was due to board a plane back to Italy on Monday.

“He stayed at the airport and waited,” Boschini told the New York Times. “But they thought he looked homeless so they kicked him out.”

Marengo got back on the subway, and was still seated on the downtown 2 train when Officer Yam stepped on board around 6:30 Tuesday morning. The 43-year-old NYPD veteran immediately recognized the disheveled looking person across from him as the missing marathoner.

Yam, a native of Hong Kong, is fluent in Spanish, which made communicating with the Italian-speaker easier. He convinced Marengo to get off the train with him and referred back to the article he’d been reading just minutes earlier.

“As soon as I got reception upstairs I pulled up the Daily News article and went ‘Tu?’” (“you” in Italian) Yam told the Daily News. “He nodded his head.”

The officer bought Marengo a cup of coffee and a doughnut and took him to Beekman Downtown Hospital, where he was treated for minor dehydration. The runner is expected to make a full recovery.

“Eight million people, eight million stories,” Yam told the Daily News. “Thank God this is one of those positive stories. It could have turned out the other way.”

Leading runners move along 4th Ave in the Brooklyn borough of New York during the New York City Marathon on Sunday, Nov. 1, 2015. (Craig Ruttle/Associated Press)