CHICAGO (CBS) — Plenty of questions remain unanswered after former U.S. House Speaker Dennis Hastert was indicted on federal charges for allegedly trying to cover up apparent hush money payments to a longtime acquaintance.

The longtime Republican lawmaker allegedly paid about $1.7 million in cash to the acquaintance – identified as Individual A in the indictment – beginning in 2010, to conceal misconduct that occurred years earlier.

Hastert started his career in politics as a state lawmaker in 1981. He served in the Illinois General Assembly until 1986, when he was elected to Congress. He served as Speaker of the U.S. House of Representatives from 1999 until he retired in 2007. Before entering politics, he was a history teacher and wrestling coach at Yorkville High School from 1965 and 1981.

According to the indictment, Individual A lives in Hastert’s hometown of Yorkville, and has known him most of Individual A’s life.

The biggest question in the case is what misconduct took place that would prompt Hastert to allegedly agree to pay $3.5 million to someone who apparently was blackmailing him.

“Apparently, it’s something that was shameful, or criminal, that he was engaged in that the blackmailer was able to blackmail him about,” said University of Illinois at Chicago political science professor Dick Simpson.

CBS 2 Security Consultant Ross Rice, a former FBI agent, said the indictment could be just the tip of the iceberg for Hastert.

“Depending on how this plays out, I think there could be other charges forthcoming. Maybe there has been some sort of plea agreement reached pretrial. I don’t know. I think what’s most intriguing to me is what was the act, or the crime if you will, that he was paying the money to Individual A to keep quiet about?” Rice said.

So far, Hastert has not responded publicly to the charges.

According to the indictment, in 2010, Hastert met with and then agreed to provide an unnamed individual $3.5 million “in order to compensate for and conceal his prior misconduct against” that person, according to federal prosecutors.

Hastert was charged with structuring the withdrawal of $952,000 in cash in order to evade the requirement that banks report cash transactions over $10,000, and lying to the Federal Bureau of Investigation about his withdrawals.

Hastert, 73, was charged with one count each of structuring currency transactions to evade Currency Transaction Reports and making a false statement to the FBI, according to an indictment returned by a federal grand jury.

Most recently, Hastert has been a lobbyist for D.C.-based Dickstein Shapiro LLP, but he resigned his position there after he was indicted.

Rice questioned whether Hastert’s case would reach trial stage, though he noted both former Gov. George Ryan and former Gov. Rod Blagojevich risked going to trial when they were brought up on corruption charges, and each of them landed in prison.

Federal prosecutors have said Hastert likely will be arraigned sometime next week.