Anthony Elgindy presented himself to the public as the champion of the small investor – a man determined to shed light on fraud, insider deals, and other malfeasance in the often murky world of penny stocks.

During opening statements yesterday in Elgindy’s trial in Brooklyn on charges of racketeering and securities fraud, federal prosecutors described the well-known San Diego stock analyst’s carefully cultivated reputation as a scam.

“Behind the facade were fraud, corruption, and betrayal at every turn,” an assistant U.S. attorney, Valerie Szczepanik, told jurors. “He was robbing from the rich and the poor.”

Elgindy is accused of conspiring with a former FBI agent, Jeffrey Royer, to steal confidential information about criminal investigations into companies. Prosecutors say Elgindy then used that information to manipulate the companies’ stock prices and, in some cases, extort money from the companies.

At the time of his arrest in 2002, Elgindy was an influential penny-stock analyst who guided a group of investors on two Web sites, including his pay subscription research and discussion service,AnthonyPacific.com.

Ms. Szczepanik said Elgindy and several alleged co-conspirators used AnthonyPacific.com as “a criminal hideout” where they traded inside information and cheated the public. She said Elgindy and his inner circle also manipulated their own subscribers. “There was no honor among these thieves,” she said.

Defense lawyer Barry Burke said, however, that Elgindy was exactly what he claimed to be: a foe of stock fraud. Mr. Burke said his client, who changed his name from Amr Ibrahim Elgindy last year and also has gone by the name Anthony Pacific, repeatedly exposed lies by companies and promoters designed to send a stock price soaring.

Elgindy was a short seller – an investor who bets a stock price will drop. Mr. Burke said Elgindy often was the lone voice deflating bogus claims.

Mr. Burke nodded yesterday to Elgindy’s checkered past, a criminal history that has landed him in trouble previously and led him to wear a wire for government investigators in the 1990s.

“Mr. Elgindy is no angel,” Mr. Burke said. Nevertheless, Mr. Burke said his client regularly provided valuable assistance to law enforcement. He said a lawyer for the Securities Exchange Commission called Elgindy “a crusader for propriety in the marketplace.”

Mr. Royer, now his co-defendant, asked Elgindy to become an informant in 2000.Elgindy declined but helped Mr. Royer with investigations, Mr. Burke said. Elgindy later offered the man a job.

Ms. Szczepanik told jurors yesterday that Mr. Royer began to steal information for Elgindy to “commit securities fraud” and, after going to work for Elgindy in 2001, used his girlfriend, also an FBI agent, to monitor investigations of Elgindy and himself.

Mr. Royer’s defense lawyer, Lawrence Gerzog, told jurors yesterday that his client used creative methods to attack securities fraud, including trading information with Elgindy, but never committed a crime.