His repeated warnings that Wall Street money manager Bernard Madoff was running a giant Ponzi scheme have cast Harry Markopolos as an unheeded prophet.

But people who know or worked with Markopolos say it wasn't prescience that helped him foresee the collapse of Madoff's alleged $50 billion fraud. Instead, they say diligence and a strong moral sense drove his quixotic, nine-year quest to alert regulators about Madoff.

"He followed through on everything he ever did. He never let up," said his mother, Georgia Markopolos, in an interview Thursday. "Some kids just let it go if it's too hard, but he wouldn't do that."

"He feels very sorry for these people that got taken," she added. "It wouldn't have happened if they would have listened to him long ago."

Markopolos waged a remarkable battle to uncover fraud at Madoff's operation, sounding the alarm back in 1999 and continuing with his warnings all through this decade. The government never acted, Madoff continued his ways, and people lost billions.

Markopolos reached his conclusion with the help of mathematicians like Dan diBartolomeo, whose analysis of the Madoff's methods in 1999 helped fuel Markopolos' suspicions.

"People should have seen the writing on the wall," diBartolomeo said.

Markopolos did not respond to multiple e-mail or phone requests for an interview.

The 52-year-old resident of Whitman, about 20 miles south of Boston, grew up in Erie, Pa., the oldest of three siblings.

His mother said her son was a little nerdy as a child, as well as occasionally mischievous and unfailingly honest. She recalled an incident where he pelted his elementary school with eggs in the middle of winter, but no one saw him. Time passed with no confession from anyone, until Markopolos stepped forward, admitted he did it, and cleaned the school himself.

Markopolos became an adept hunter and fisherman as he grew up, like many from the rural area, but also showed early aptitude at academics, as well as a willingness to question authority.

"He used to challenge the teachers," his mother said with a laugh. "He'd tell them he had the right answers, but they had the wrong questions."

Markopolos graduated from Cathedral Prep in Erie in 1974, then in 1981 from Loyola College in Maryland, which his mother said he paid for on his own. After time in the Army and in the financial services field, he earned a graduate management degree from Boston College in 1997.

By 1999, he was working for Rampart Investment Management Co. and charged with doing competitive research on Bernard L. Madoff Investment Securities, which was using a similar investment strategy as his company, but far outperforming it. Part of Markopolos's research included a visit to diBartolomeo, whom he knew from his professional circle.

"I think he was curious about how his competitor was doing so much better than they were," diBartolomeo recalled.

Researching Madoff's numbers, using data the firm distributed to prospective investors, diBartolomeo concluded within hours that it was impossible for Madoff to get the returns he reported while using the strategy he said he used.

"As the market goes up and down, this strategy should have done a little better or a little worse, just like everybody else," he said. "Instead, it appeared to be indifferent as to whether the market went up or down. They made money all the time."

Markopolos complained to the SEC's Boston office in May 1999, saying it was impossible for the kind of profit Madoff was reporting to have been gained legally.

But Madoff continued to thrive, even as Markopolos continued to pursue the case.

In 2005, he submitted a report to the SEC saying it was "highly likely" that "Madoff Securities is the world's largest Ponzi scheme." In the report, he says he knew his research could ruin people's careers and asked the SEC be discreet about circulating the report and his name.

"I am worried about the personal safety of myself and my family," he wrote.

The report highlights 29 "red flags" about Madoff's business, among them the returns of a third-party hedge fund managed by Madoff's firm which had negative returns in just seven on the 174 months Markopolos analyzed.

"No major league baseball hitter bats .960, no NFL team has ever gone 96 wins and only 4 losses over a 100 game span, and you can bet everything you own that no money manager is up 96% of the months either," he said.

His warnings were heard too late, and he's become a symbol of a botched oversight of Madoff by the SEC. His mother says the father of three boys under 5 has been bombarded by media requests. Now, a man who tried to be heard for years is going to lay low for a bit, she said.

"Right now, he's out relaxing some place," he said. "I can't even get in touch with him."