Best Buy Company, Inc., has expanded its investigation of alleged misconduct by former CEO Brian Dunn-and it's exploring whether some of the company's top executives improperly withheld information from its board, according to a Star Tribune report.

A month ago, the Richfield-based electronics retailer announced that Dunn had resigned from his top post, and it was subsequently uncovered that the former chief executive left the company amid an investigation into allegations involving his conduct with a female subordinate.

“If leadership was found to suppress legitimate grounds for an investigation, then that would warrant discipline,” Jacob Frenkel, who leads the white-collar crime practice at Maryland-based Shulman Rogers, told the Star Tribune.

In addition to looking into whether there was improper conduct on the part of top company leaders, Best Buy's investigative team is also exploring whether Dunn used company-leased aircraft in connection with the alleged improper relationship with the female worker, according to the Minneapolis newspaper, which cited an unnamed source with knowledge of the investigation.

Best Buy has reportedly leased airplanes and chartered aircraft services from Best Jets International to the tune of $3.56 million over the past five years. Minneapolis-based Best Jets is based in Minneapolis and owned by Best Buy Chairman and founder Richard Schulze.

Best Buy officials declined to provide comments to the Star Tribune about its report.

“As we have said, the investigation is ongoing,” company spokesman Greg Hitt of H&K Strategies told the newspaper. “The board's findings will be made public and appropriate action will be taken if warranted.”

Frenkel told the Star Tribune that Best Buy could seek restitution from Dunn if the allegations are true-possibly by requiring him to reimburse the company for the use of corporate jets.

Best Buy hasn't paid Dunn's annual performance bonus, which it said in a proxy statement is “pending the results of an ongoing independent investigation by the audit committee of the board into Mr. Dunn's personal conduct.”

Citing an unnamed source who is close to Best Buy, the Star Tribune reported that company investigators have already spoken to the 29-year-old female subordinate with whom Dunn is alleged to have had a relationship, and she has retained a lawyer.

To read the full Star Tribune story about the investigation into Dunn's personal conduct and the new developments surrounding it, click here.