Homeless man finds $42,000.........turns it into the police.

A homeless good Samaritan who turned in a lost backpack stuffed with nearly $42,000 yesterday was hailed by his fellow down-and-outers as a guy with a “great heart.”

“People will probably tell him he’s nuts, but homeless people are the first to help you out,” said Bob Boisselle, who, like the nameless humanitarian, stays at the city’s Long Island Shelter on Boston Harbor. “They don’t have anything, but they’ll give you what they do have.”

On Saturday night, Boston police said, the man turned in a lost backpack he had found at South Bay Mall in Dorchester — a backpack Boston police said contained $2,400 cash and $39,500 in American Express Travelers Cheques.

The man, who police declined to identify by name, flagged down officers and told them he found the black backpack in front of T.J. Maxx.

“He’s got a great heart,” said Aaron Toye, who stays at a different shelter in the city. “He did the right thing.”

Police said in addition to the money, the backpack contained passports “and various personal papers.”

Police were contacted an hour later by a mall customer reporting he’d lost a backpack “containing a large sum of money.”

Police said the rightful owner was identified by his Republic of China passport and the property was returned to him.

The anonymous hero must have acted out of a keen sense of empathy, his fellow street-dwellers said yesterday as the story made its way around the city’s shelters and alleys.

“Homeless people,” said Boisselle, a former western Massachusetts landscape designer who has been on the streets since 2005, “know what it’s like to be down and out.”