In the two years since George C. Venizelos took over the FBI's Philadelphia division, the North Jersey native has developed a sense of how corruption works here.

The people and public officials are no more inherently corrupt than in other metropolises, according to Venizelos. But the government structure and history sometimes make the conditions ripe for graft.

Take a densely populated area, add hundreds of agencies, departments, municipalities, and elected positions, and fold in a pay-to-play culture. Then consider that Philadelphia has traditionally had ensconced political power brokers, the kind few are willing to cross, he said.

"The intimidation factor is huge in this city, and that's something we're trying to fight," Venizelos said.

On Monday, he gathered with a half-dozen other state, federal, and local law enforcement officials to announce an admittedly small step but one they hope will make a difference, a new confidential hotline to encourage and field tips on public corruption.

"The most difficult part of corruption cases is getting people to call us," Venizelos said. "That's one area we're trying to increase here, by giving somebody an easy way."

Billboards with the number, 1-855-FBI-TIPS will soon begin flashing on area highways. The bureau also takes confidential and anonymous e-mail tips at philadelphia.complaints@ic.fbi.gov.

Joining Venizelos were U.S. Attorney Zane David Memeger, Philadelphia Police Commissioner Charles H. Ramsey, State Attorney General Linda Kelly, Pennsylvania Inspector General Kenya Mann Faulkner, and City Inspector General Amy L. Kurland.

Each has at times spearheaded corruption investigations and, they said, increasingly work together.

But the lion's share of the work often falls to the FBI. About a dozen FBI agents are assigned to its public corruption squad, the same one that helped win convictions against former City Treasurer Corey Kemp and State Sen. Vincent Fumo.

Last year, Venizelos formed a separate squad that, working with city investigators, focuses primarily on law enforcement corruption.

"Preventing the next terrorist tack is always our No. 1 priority. But when you look at our criminal program, corruption is the priority," Venizelos said in an interview before the announcement. "It's an area that the FBI is expected to work. . . . In most instances, if we don't do it, a lot of times it won't get done."

The prosecutors and agents said that many corruption cases begin with tips from the public or inside offices.

Kurland said the arrest of three businessmen on bribe charges this year began when one of the defendants tried to hand an envelope of cash to a City Hall employee just to get a leg up on approvals or permits.

"Great cases often start with tips from citizens," she said.

Venizelos said the tip line is similar to one used, with some success, by the FBI's Pittsburgh division. He said it isn't a response to any perceived uptick in graft among public officials or employees, although he noted the struggling economy opens the door to more corruption.

Venizelos cited the explosion of charter schools in recent years as an area that has become ripe for wrongdoing and scrutiny.

In July, a federal grand jury indicted Dorothy June Hairston Brown, a longtime Philadelphia educator and charter school founder, for an alleged fraud that prosecutors said brought the loss of $6.5 million in taxpayer funds.

"When times get tough," the FBI agent said, "people get desperate, and when people get desperate they do things they wouldn't normally do."

Contact John P. Martin at 215-341-2597, at jmartin@phillynews.com or follow @JPMartinInky on Twitter.