SCOTRUN - He was fired from one company, then another, then another. And still Anthony Diaz continued handling other people's money.

The smooth-talking securities salesman affiliated with 11 investment firms in 15 years, getting booted from five of them and resigning from another amid customer complaints and rules infractions. Yet his checkered employment history never seemed to slow him down on his way to earning millions by pushing high-fee, high-risk "alternative investments."Now under federal criminal indictment for fraud - he has pleaded not guilty - and with dozens of former clients lodging complaints, Diaz illustrates what can go wrong when investment firms hire problem brokers.It happens with alarming frequency. An academic study from March found that 15 to 20 percent of the brokers at some of the largest financial services firms in the country, including one that employed Diaz, have disciplinary records. Moreover, nearly half of financial advisers fired for misconduct find a new job in the industry within a year - and are at greater risk of reoffending, according to researchers at the universities of Chicago and Minnesota.The researchers also found that brokers with a propensity for ripping off their customers tend to migrate to certain firms, suggesting the firms "specialize" in misconduct and "cater to unsophisticated consumers.""A lot of these guys are real hustlers," said Jacob Zamansky, a securities lawyer who represents investors, explaining why firms would take a chance on an unethical broker. "It's all about the money, and it's a risk-reward. … This is a big problem, perhaps one of the biggest."The issue has caught the attention of federal lawmakers and regulators."It's disappointing that some of these hiring practices continue to take place within the industry," said Nancy Condon, spokeswoman for the Financial Industry Regulatory Authority, Wall Street's self-policing body.'A total, total rip-off'Pennsylvania retiree Vincent Sylvester, 69, said he invested nearly all of his $500,000 nest egg with Diaz after the financial adviser guaranteed him returns of 8 percent and more. Sylvester said Diaz inflated his net worth to qualify him for the investments, didn't explain the risk and failed to tell him his money would be tied up for years.Now he and his wife are making barely $400 a month on their savings - a return of less than 1 percent - and their retirement is less comfortable than it might have been. Sylvester is dealing with bladder cancer on top of his financial stress."The whole thing was a total, total rip-off," said Sylvester, who worked in the real estate department of a homebuilder. "It took me a lot of years to save this money, and a lot of hard work, and unfortunately you've got guys like him who don't really care."Federal prosecutors allege Diaz advised his clients to put their money in real estate investment trusts and equipment leasing partnerships, types of higher-risk, illiquid "alternative investments" geared to wealthier, more sophisticated investors.He had them sign blank documents, then he falsified their net worth, income and risk tolerance to make it appear they met the suitability requirements of the products, according to a grand jury indictment."I had no idea they were super high-risk," said Bruce Kilby, 67, of Scotrun, a retired pharmaceutical company worker who invested about $350,000 with Diaz. The financial adviser, Kilby said, "was a very fast talker, and when you asked questions that he didn't want to answer, he more or less talked down to you."Kilby won a $220,000 arbitration award against Diaz, who has challenged it in state court.Diaz's attorney, Darren Gelber, said his client rejects the allegations."It is his very, very strong and fervent belief that everything he did was proper and legal," Gelber said.Seeking answersDemocratic Sen. Elizabeth Warren of Massachusetts and Republican Sen. Tom Cotton of Arkansas have asked Wall Street regulators to address what they're doing about firms that routinely employ brokers with a history of fleecing clients.The Financial Industry Regulatory Authority has until June 15 to respond, but agency chief Richard Ketchum has already warned investment firms that routinely employ high-risk advisers to expect "searching questions" about "the special supervisory steps they have taken to ensure no further bad actions."New federal regulations, meanwhile, would require brokers to put their clients' interest ahead of their own when giving retirement investment advice. Wall Street lobbying groups sued last week to block the rules, arguing they're too burdensome and subject brokers to too much liability.Even with so many rule-breaking brokers still in business, Diaz's serial firings stand out. He's the only one of the nation's 650,000 licensed brokers to have been fired more than three times, according to an analysis conducted for The Associated Press by Securities Litigation and Consulting Group Inc.Why was he able to land on his feet so many times?"It's about greed," said attorney Albert Murray Jr., who represents about 30 former clients of Diaz.