NEW YORK — Best Buy CEO Brian Dunn, 50, abruptly resigned Tuesday after the consumer electronics chain launched an internal investigation into his “personal conduct.”

Best Buy released a statement late Tuesday saying it is conducting the probe after earlier only saying the departure was a “mutual decision.” The chain would not give any specifics on the circumstances surrounding the investigation of Dunn, a 28-year Best Buy veteran who had been CEO since 2009.

“Certain issues were brought to the board’s attention regarding Dunn’s personal conduct, unrelated to the company’s operations or financial controls, and an audit committee investigation was initiated,” according to a company statement issued late Tuesday. “Before the completion of the investigation, Mr. Dunn chose to resign.”

Best Buy said Tuesday that board member Mike Mikan, 39, will serve as interim CEO while the company searches for a permanent replacement.