DETROIT » It was a typical frigid winter night in this city, only now a historic blizzard was on the way. Robert Jones Jr., homeless and jobless for more than a decade, calculated his next move.

This 62-year-old resident of Detroit’s North End knew the slice of pizza he had just been given by a store clerk would not last. He needed some quick cash. So on his way home he detoured down familiar railroad tracks, looking for the industrial junkyard where for many years, he said, he could grab loose pieces of metal to sell, usually without repercussions. Yet within minutes, his instincts started to speak up.

"Something in the back of my mind said, ‘Get out of here,’" recalled Jones, who had been arrested in this yard six years earlier. Too late. Security guards stopped him, and the police came. And as had happened before, the only metal he left with was a pair of handcuffs slapped to his wrists.

For generations, scavengers have prowled this city with impunity, pouncing on abandoned properties and light poles to pilfer steel, copper and other metals they could trade for cash at scrapyards. The practice left tens of thousands of buildings so damaged that they could not be restored, turning places like the North End into grim cityscapes that appeared to have been ravaged by a tornado.

In recent years, the city has become serious about fighting back. It razed dozens of rickety homes – lucrative scrapping targets – in this neighborhood alone in the past year. Residents have become increasingly vigilant about chasing scrappers away from their blocks, lawmakers have enacted rules making it more difficult to turn a quick profit from scrapping, and the police and private and public agencies have stepped up enforcement efforts.

The battle has been critical in places like the North End, a community with both expansive blight and bright economic potential, given its proximity to the city’s cultural and commercial heart.

Yet even as the crackdown on scrapping helps make neighborhoods like the North End look better, it is sounding a death knell for part of the underground economy that took root during Detroit’s long years of decay. And with that, people who continue to have bleak job prospects in the city’s stubbornly sluggish economy are finding their struggle to survive that much harder.

Jones subsists by Dumpster diving, doing odd jobs and, when he sees the opportunity, scavenging scrap metal. It is a dreary existence, evident in his drowsy eyes, a hardened face surrounded by a gray mane, a voice groggy from endless nights of sleeping in the biting cold and the torn and smeared jackets he wears in layers.

He never graduated from high school because his mother died when he was a senior and he was too anguished to continue, he said. He has seven children by several women, but he lost contact with them in part because of his drug addiction, which he said he kicked six years ago. He avoids his three siblings even though, he said, he believes they would help him if he asked. He lives in an abandoned house.

"I don’t want them feeling my pain," he said of his siblings, noting that his sister cried the last time she saw him.

Jones was arrested at the yard on Jan. 31 while he and another North End man were toting a large bag with six pieces of scrap metal, including four heavy discs and a 14-inch pipe, according to a police report. A few days later, his file crossed the desk of Sgt. Rebecca L. McKay, who, as head of the police unit that handles metal theft, has gained a reputation as a relentless scrapping enforcer. Now she was faced with the difficult decision of whether to come down hard on a man who was barely surviving.

"I can’t say that I don’t have sympathy for these people," McKay said. "But they’re breaking the law. Not only are they breaking the law, but they’re affecting the community around them by doing it."

Ridding the city of illegal scrappers, McKay said, starts with squeezing those who reward the thieves. "Where there’s no buyer, there’s no seller," she said.

So her four-person unit, which also handles graffiti and illegal dumping, spends much time making sure that scrapyards follow the law. On one sunny Friday afternoon in early February, she ventured out to visit a few yards in southwest Detroit, riding with one of her investigators, Detective Laura Splitt, in one of the department’s unmarked sport utility vehicles.

Her mission that afternoon was to gather intelligence on Jones and five other men accused of stealing from the industrial scrapyard where he was arrested.

For his part, Jones says he wants to see new money and new energy come into the city, into this neighborhood. He would welcome a full-time job if he could find one, he said. Detroit’s unemployment rate was about 12 percent at the beginning of this year. But he does not believe progress will trickle down to people like him. "I ain’t going to benefit from it," he said. Later, turning his eyes toward the cloudy sky, he added, "I don’t see no $100 bills falling."

Before Jones can think about money, he has to worry about the law nipping at his heels.

McKay was unable to come up with data from the scrapyards to confirm that Jones regularly sold to them. Southwest Metals, which was linked to nearly half of her cases last year, stalled so much in responding to multiple requests for information, she said, that she filed numerous citations against the business.

But, McKay said, while looking over the investigative notes from Jones’ arrest, she saw that he had indicated that he planned to sell the scrap metal he was accused of taking from the industrial yard. For her, that was enough to justify felony charges, and she referred the case to the county prosecutor’s office, which has issued a warrant for Jones’ arrest.

Jones might earn very little from scrapping, McKay said, but she sees him as part of a cycle that destroys properties and, in turn, the city.

"If we can’t get a handle on the Robert Joneses of the city, we’re not going to be able to get a handle on the problem at hand," she said.

Yet Jones insisted that although he had entered the industrial yard looking for scrap metal, he had taken nothing. And before that moment of weakness and need, he said, he had sworn off illegal ways. He long ago stopped breaking into buildings to steal scrap, he said.

Occasionally these days, he stumbles upon a bit of luck. Recently someone dumped stainless steel cages on a corner field in the North End, allowing Jones to help himself to the pile.

"That’s what I do," he said. "One heartbeat at a time. Until Jesus calls me."

© 2015 The New York Times Company