Kroger CEO and Chairman Rodney McMullen resigned Monday following an investigation into his conduct that was “unrelated to the business.”

McMullen, a lifelong Kroger employee, was only three days away from the fourth quarter earnings conference call. Kroger is among the largest supermarket operators in the United States.

“The Kroger Co. (NYSE: KR) today announced that Chairman and Chief Executive Officer Rodney McMullen has resigned from the Company following a Board investigation of his personal conduct that, while unrelated to the business, was inconsistent with Kroger’s Policy on Business Ethics,” Kroger wrote in a press release offering no further detail.

In 1978, McMullen began working as a store clerk and bagger at a Kroger store in Lexington, Kentucky. From there, he received promotion after promotion until he became the chief financial officer in 1995 and then chief operating officer in 2009. McMullen served as CEO since 2014 and chairman since 2015.

Ronald Sargent will take his place as chairman of the board of directors and interim CEO. Sargent was previously the CEO of Staples.

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This came over two years after Kroger failed to buy and merge with the Albertsons grocery chain for $24.6 billion. McMullen was slated to head the merged company until two judges struck down the merger. Together with Albertsons, Kroger would have had a share of approximately 12% of the U.S. market, according to 2021 statistics.

Kroger shares had fallen by over 2.6% as of Monday afternoon.