May 14 (Reuters) - Best Buy Co Inc said that former Chief Executive Officer Brian Dunn violated company policy by engaging in an extremely close personal relationship with a female employee and that the chairman of the board acted inappropriately when he failed to bring the matter to the audit committee when he first learned about it.

Best Buy also said on Monday that Hatim Tyabji, currently the chairman of its audit committee, would succeed Richard Schulze as chairman of the board, effective June 21.