The John Buck Co., a real-estate investment firm whose executives contributed substantially to the campaign of Chicago Mayor Rahm Emanuel, has earned more than $1 million in fees for managing city pension money. The details of the company's fees emerged amid scrutiny over the propriety of the campaign contributions from company executives.

According to a newly released document from the Chicago pension system, the taxpayer fees paid to the John Buck Co. from one Chicago pension fund increased when Emanuel took office. In the year before he took office, the John Buck Co. was paid $161,141 in fees by the Laborers' & Retirement Board Employees' Annuity & Benefit Fund of Chicago (LABF). The next year -- when Emanuel assumed office -- those fees jumped to $262,500. In 2012 and 2013, the fees increased to $300,000 per year. Public documents from LABF say the decisions to move pension money into the system's current John Buck investments were initiated in 2006 and 2009.

The document was obtained by International Business Times through a Freedom of Information Act request to one of the five Chicago pension funds in the city's $23 billion retirement system.

When combined with the more than $334,000 in fees paid to the company by the Municipal Employees Annuity and Benefit Fund (MEABF) since 2011, Chicago taxpayers have delivered more than $1.1 million in fees to the John Buck Co. since Emanuel took office. Emanuel appoints officials to the boards that oversee the pension investments.

Executives at the John Buck Co. are collectively among Emanuel's top campaign contributors. In all, as reported by IBTimes, they have donated more than $74,000 to Emanuel's campaigns, and $10,500 more to a political action committee that supports the mayor.

Legal experts, corporate compliance attorneys, former prosecutors and former Securities and Exchange Commission officials have said donations to Emanuel from firms managing city pension money may violate a 2011 SEC pay-to-play rule and a municipal executive order banning contributions to city officials from city contractors.

At a City Hall press conference Tuesday, Chicago lawmakers announced they are requesting an SEC investigation into the contributions. An Emanuel spokesperson told DNAInfo: "The donations are fully compliant with the law and the higher standards the mayor voluntarily imposes‎ on himself per his executive order."