Scott London, a Los Angeles partner in one of the nation's largest accounting firms, says it began four years ago.

By his account, a friend with money trouble was poking around for information on Herbalife Ltd. and Skechers USA Inc., two Los Angeles-area companies whose audits London personally oversaw. Soon, he says, he was passing inside tips on the companies that resulted in as much as $100,000 in profit for his buddy.

In return, he says, he collected "about $25,000" in cash, was treated to fancy dinners and received a Rolex watch as a gift.

On Tuesday, London and his company, KPMG, were caught up in an insider-trading scandal that rocked Wall Street.

The furor began late Monday when KPMG announced it had fired a high-ranking staffer, later revealed to be London. The accounting giant said the executive had allegedly been involved in insider trading of prominent companies whose audits he handled.

Full coverage: KPMG auditor accused of insider trading

On Tuesday, those firms — nutritional supplement maker Herbalife and footwear company Skechers — said KPMG had abruptly resigned as their outside auditor because of the alleged misconduct.

Trading in stocks of the two local companies was temporarily suspended. That was particularly significant for Herbalife, which already was engulfed in a separate controversy that had investors on edge.

The Los Angeles company has been caught up in a tug of war with a hedge fund manager who has accused the firm of running a well-disguised pyramid scheme.

The two-hour trading halt in its shares brought a whirl of speculation that Herbalife was about to uncork damning news about itself. The fast-moving events surprised even veteran Wall Street watchers.

"It's a shocker," said Mark DeFond, a professor at USC's Leventhal School of Accounting. "I've certainly never heard of anything like this happening."

The Justice Department is investigating the insider trading allegations, people familiar with the matter said.

KPMG was approached by the Justice Department late last week and told that London, who was a partner in KPMG's office in downtown Los Angeles, was under investigation, according to a person briefed on the matter. London was fired less than 24 hours later.

The firm in a statement described the executive as a "rogue" employee who "acted with deliberate disregard for KPMG's long-standing culture of professionalism and integrity."

Herbalife said it may need a year to find a new independent auditor and have its financial statements approved, analysts said. The company's ability to borrow could be compromised. It issued a statement Tuesday rejecting notions that it could be delisted by the NYSE.

It's the latest setback in an already tumultuous year for the company. In December, Bill Ackman of Pershing Square Capital Management publicly branded Herbalife's multi-level marketing set-up a "pyramid scheme" that pays millions of dollars to distributors who recruit new sellers while underfunding the rest.

Herbalife denied the allegations, claiming that Ackman was trying to manipulate the company's market performance. But the damage was done — its stock tumbled as low as $24.24 a share from as much as $73 a share last April.

Former KPMG auditor London said that "there is absolutely nothing wrong" with Herbalife's financial statements and that he regrets his actions.

Neighbors and associates who knew London never expected him to be embroiled in such a scandal.

The 29-year KPMG veteran lives in a two-story house in an Agoura Hills cul-de-sac. He has a passion for baseball and pitched batting practice for his son's high school team.