WASHINGTON — A Chicago Sun-Times analysis of auto mileage reimbursements for scandalized Rep. Aaron Schock, R-Ill., reveals he may have been inflating claims on not just one but two vehicles, starting in 2008, when he was first running for Congress.

The Sun-Times has calculated that since last month Schock has reimbursed taxpayers at least $127,590 – almost three-quarters of his annual salary — for his office redecoration, mileage and a charter flight to a Bears.

Schock, 33, from Peoria, announced Tuesday he will resign from Congress on March 31. That comes after revelations from news outlets, including the Sun-Times, about questionable campaign and official spending and other business dealings.

The reimbursements and pending resignation did not shield Schock from a Justice Department investigation.

The Sun-Times reported last week that FBI agents based in Springfield were in Washington on Thursday, handing out subpoenas and questioning potential witnesses. In April, a grand jury in Springfield will be hearing testimony.

Schock resigned the day after a Sun-Times report that he billed taxpayers for mileage on a 2015 Chevrolet Tahoe he purchased with campaign funds. Illinois vehicle records, obtained by the Sun-Times through the Illinois Freedom of Information Act, showed the title for the SUV was in Schock’s name.

But it is taxpayer- and campaign-funded mileage payments on his previous SUV — a 2010 Chevrolet Tahoe — that are far more legally dangerous to Schock.

Schock made the surprise announcement that he was stepping down as his team of legal and communication advisers knew the Sun-Times and Politico had obtained records from the Illinois Secretary of State that could confirm that Schock was billing taxpayers and his campaign funds for vastly more miles than that 2010 Tahoe was ever driven.

How Schock got caught

On July 19, 2014, the day Schock bought the 2015 Tahoe from Green Chevrolet in Peoria, he made a big mistake.

He did it in the time it took to sign his name.

That’s how he got caught.

When cars are bought and sold in Illinois, the law requires that the current odometer readings be included on the transfer documents.

On July 19, 2014, state records reveal Schock signed a power of attorney showing that his 2010 Tahoe had 81,860 miles. By the time the transfer of the 2010 Tahoe to a Peoria car dealer was finalized, the odometer had 81,886 miles, state records show.

When Schock bought that 2010 Tahoe on Nov. 24, 2009, only 4 miles had been rolled up on the odometer. Schock signed an “official odometer statement” noting the 4 miles on Nov. 24, 2009.

Schock tripped up because on July 19, 2014, he locked in a finite number of miles that 2010 Tahoe was driven.

The Sun-Times — as did Politico — dug into Schock’s official House disbursement records and reports filed with the Federal Election Commission for his Schock for Congress and for his GOP Generation Y campaign committees.

Those documents showed what Schock was paid for mileage. The Sun-Times translated the cash payment into estimated miles by applying the IRS mileage reimbursement rates, which ranged from 50 cents a mile to 58.5 cents a mile between 2008 and 2014.

By the end of 2013, Schock had already billed taxpayers for 111,856 miles – more than the Tahoe was driven.

And by July 2014, when Schock got rid of the 2010 Tahoe, Schock had billed taxpayers for a total of 123,130 miles.

Add to that payments covering 50,744 miles from his two campaign funds — most in 2014 — and the total mileage claimed was about 173,874.

Because the odometer was frozen at 81,886, Schock overbilled for an estimated 91,988 miles.

More red flags: Schock’s Envoy mileage

A Sun-Times examination of Schock’s mileage claims for a GM Envoy he owned before the 2010 Tahoe raises more red flags.

Schock was first elected to Congress in 2008 and sworn-in to the House in January 2009.

He bought the Envoy on May 18, 2007, with 24,316 miles on the odometer, state records show. When Schock sold the vehicle, there were 77,446 miles on the odometer as of Dec. 30, 2009 — 53,130 miles driven.

House disbursement records for 2009 show Schock billed taxpayers for an estimated 32,698 miles; Schock’s campaign reports show that in October 2008, Schock was reimbursed for about 9,618 miles.

In all, Schock billed taxpayers or his campaign fund for an estimated 42,316 Envoy miles – almost all the miles driven on the Envoy when he owned it.

Schock’s taxpayer reimbursements

Schock appears to have tried to dilute some of his legal and public relations problems by reimbursing taxpayers for some of the money he collected.

In February, Schock repaid $40,000 for his “Downton Abbey” office redecoration. In March, he repaid $1,237 after the Sun-Times revealed taxpayers paid for a charter plane to fly him from Peoria to Chicago for a Bears game.

Last Tuesday, Schock reimbursed all official — not campaign — mileage he was paid since joining Congress. The Sun-Times has estimated that since 2009, Schock has billed taxpayers an estimated $86,353 for his official mileage. All totaled: $127,950.