Gianclaudio Marengo, left, was found on the 2 train by Officer Man Yam, right, aboard the 2 train, police said. View Full Caption NYPD

MIDTOWN — An off-duty NYPD officer Tuesday morning looked up from his news story about an Italian runner who disappeared after the New York City Marathon to find the man there on the train with him, sources said.

The recruitment officer, Man Yam, got off the train about 7 a.m. at Penn Station with Gianclaudio Marengo, 30, who'd spent the two days since the race lost in the city, riding the subway, eating pizza, sleeping on the street and trying to find his Italian race mates, officials said.

Marengo, who had last been seen at the finish line of the marathon on Sunday about 3 p.m., was then taken to Lower Manhattan Hospital and treated for dehydration, sources said.

He was otherwise in "good condition," NYPD officials said.

"He has already recovered substantially and is in good humor," said officials at his Italian rehab clinic which had organized his team's marathon run.

Marengo's two day ordeal began when he realized he'd lost the note with directions back to his team's Astoria hotel, the Sleep Inn Hotel at 38-71 13th St., according San Patrignano, an Italian rehabilitation clinic that treated the runner for drug addiction.

Marengo stayed in the area for a while, hoping to run into a familiar face, clinic officials said.

He grabbed a slice of pizza and slept overnight on the street, clinic officials said.

The next day, he tried to meet his friends at the airport, but was turned away because he didn't have proper documents, returning to Manhattan for another night on the streets, officials said.

Marengo and his racing pals will soon fly back to Milan, clinic officials said.

Marengo had been part of San Patrignano for the past three years, where he studied carpentry and joined their running team, officials said.

"He is certainly a fragile person, vulnerable, and very emotional who after years of drug abuse had found an opportunity for recovery in San Patrignano," officials said.

"In running, a sport enjoyed by many young people in the community, he had discovered a new passion, so great that the community decided to reward it by putting him in the San Patrignano running team, that for the last three years have participated in the New York City Marathon," officials said.

Marengo disappeared wearing a turquoise shirt, black shorts and a racing bib with the number 23781, police said.

Marathon records show that the number on Marengo's bib belongs to a man named Antonio Boschini, 57, who ran the race in 4 hours and 44 minutes.

Race photos show someone who resembles the missing man in photos distributed by police.

"[Marengo] was not a registered entrant in the field. We are currently looking into the details surrounding the registration of the bib that he ran with," said Chris Weiller, a spokesman for race organizers, the New York Road Runners.

"We are thankful to the NYPD for their assistance in finding the runner from Italy who was separated from his group," Weiller said.