Amid a federal corruption investigation that has snared a longtime top adviser, Rep. Chaka Fattah (D., Pa.) said Wednesday that he had "never engaged in any illegal conduct" during his long political career.

"I would never do anything to embarrass my family or my constituents," Fattah said in a statement provided by his office in response to an interview request from The Inquirer.

The statement echoed a theme the congressman sounded Tuesday morning in a 16-minute radio appearance on WURD-900 AM, during which he would not say whether he had played a role in receiving and repaying an illegal $1 million loan to his 2007 campaign for mayor of Philadelphia.

"The one thing is, I'm not a lawyer, I'm not going to engage in it," Fattah said in response to a question from host Solomon Jones. "I'm not going to respond to an allegation that hasn't been made."

Gregory Naylor, Fattah's former chief of staff and a longtime confidant, pleaded guilty last week to federal charges in the loan scheme and agreed to become a cooperating witness in an ongoing probe.

Federal prosecutors called the loan, from former Sallie Mae chief executive Albert Lord, a campaign contribution designed to evade the city's $5,000 limit in Fattah's mayoral campaign. The plea memo said the loan was partly repaid with a federal grant routed through two nonprofits and a political consultant associated with the congressman.

Meanwhile, House records show that Fattah's top aide on the House Appropriations Committee was subpoenaed earlier this year to testify in a federal criminal case. The aide, Michelle Anderson-Lee, wrote to Speaker John Boehner (R., Ohio) on April 21, telling him "I have been served with a subpoena, issued by the United States District Court for the Eastern District of Pennsylvania, for testimony in a criminal case."

It could not be learned what, if any, connection that subpoena had to the criminal investigation involving Naylor.

Anderson-Lee was formerly Fattah's chief of staff, but became his director of appropriations in 2011, around the time Fattah became the top Democrat on the subcommittee handling commerce, justice, science, and related agencies.

'Very enthusiastic'

House rules require members and congressional aides who are subpoenaed to notify the speaker. Fattah's office had no further information about the subpoena, a spokeswoman said.

Fattah had notified Boehner in March that his office had been subpoenaed by the same court for documents, but his letter then did not mention testimony. At that time, he vowed to fight part of the subpoena that sought material he said he believed was not relevant or was protected by congressional privilege.

Several times Tuesday, Fattah told Jones that the federal investigation had been going on for seven years.

"They looked at everything else I've ever touched or worked on," Fattah said. "They've been very enthusiastic in their efforts."

Jones, who began hosting a morning show on WURD on Tuesday, was an adviser on Fattah's unsuccessful 2007 mayoral campaign and later worked part time on his congressional staff from 2009 to 2013, federal records show.

'How this unfolds'

Why would Naylor, a respected political operative, have pleaded guilty if the charges were baseless? Jones asked his former boss.

"We'll have to see how this unfolds, but you know, why someone did what they did is not something I can respond to," Fattah said. He added, "I'm prepared to be judged by my work."

Fattah also complained about the Philadelphia media during his WURD appearance, saying reporters had largely ignored him until there was a "cloud of suspicion."

He noted that federal investigations involving members of Congress do not always pan out.

He cited former Rep. Curt Weldon, a Delaware County Republican, who was defeated in 2006 a few weeks after the FBI raided his daughter's home looking for evidence in an investigation of whether he had used his position to help her lobbying company. No charges were ever filed.