Former U.S. House Speaker Dennis Hastert has conducted private business ventures through a little-known government office that has cost taxpayers about $1.8 million, a Tribune investigation has found.

Federal law allows former House speakers to maintain a government-financed office for up to five years to wind down matters relating to their tenure. They are not permitted to use the office for financial gain.

But the Tribune found that a secretary in the ex-speaker's government office used email to coordinate some of his private business meetings and travel, and conducted research on one proposed venture. A suburban Chicago businessman who was involved in the business ventures with Hastert said he met with Hastert at least three times in the government office to discuss the projects.

A government watchdog group, told of the Tribune's findings, called for an ethics investigation into Hastert's use of the Office of the Former Speaker in west suburban Yorkville.

Hastert, an Illinois Republican, said he did not misuse the office. "I didn't work on any private business out of there," he said.

Hastert, 70, spent nearly 21 years in Congress, leading the House for eight years until January 2007 and leaving later that year. He now works as a lobbyist for Dickstein Shapiro in Washington and has a consulting business, Hastert & Associates, in Illinois. Meantime, he collects three government pensions totaling about $106,000 a year.

Court records, interviews and dozens of emails link the Office of the Former Speaker to J. David John, a Burr Ridge businessman who made six of the emails public in a lawsuit in DuPage County against Wheaton College, a small, evangelical Protestant institution.

John, 48, and Hastert are both graduates of Wheaton. John said in court papers that he met Hastert about 16 years ago, and both men wrestled at Wheaton and remain fans of the sport.

John graduated from Wheaton in 1985 and later earned a master's degree from Columbia University and an MBA from the University of Chicago. He is the managing U.S. partner for Interstate, a London-based firm that specializes in product and brand identity and has worked with Formula One auto racing.

By 2008, Hastert teamed up with John on several ventures, including proposals for a Formula One-quality racetrack in Southern California and sporting events in the Middle East, John said in court records.

Hastert was to receive 7 to 10 percent of the managing partners' proceeds from each project, John said in court papers. Hastert, though, said he did not have a contract to do business with John and was helping a friend.

Lisa Post, a secretary in the Office of the Former Speaker who handles Hastert's schedule, was in contact with John on the projects. Post used the email address to communicate with John regarding his and Hastert's business travels and meetings from 2008 through 2010.

In an email about the racetrack, Post asked John to call her at the Office of the Former Speaker and gave him an office cellular telephone number. "I talked with the Speaker about this project/trip and I wanted to pass on a few things to you," she wrote in the Oct. 16, 2008, email.

Weeks later, on Dec. 8, Post sent John an email saying she had conducted research related to the racetrack project and shared with Hastert "what my research turned up."

Hastert told the Tribune he was unaware of Post conducting research and saw no problem with Post's use of office email to communicate with John. He said Post, who is paid $116,365 a year as a federal employee, handles his schedule "24/7."

"What she had to do was make people on the government side and the nongovernment side know the time I was available," Hastert said.

Post, speaking to a reporter during a September visit to the office, said her job in the Office of the Former Speaker was, "The same as it's always been, which would be to manage the speaker's schedule." She would not elaborate and declined to answer follow-up questions relating to the emails between her and John.

The amount spent so far by the ex-speaker's office — about $1.8 million — does not include spending since June, and Post declined to provide up-to-date figures.

While Hastert insisted he did no private business through the office, a letter written by the ex-speaker indicates that the California racetrack project was indeed a personal business venture for him.