Here's what you should know about Kroger CEO Rodney McMullen, who resigned following "a board investigation of his personal conduct."

Under his leadership, Kroger has positioned itself as a formidable competitor to Walmart, Amazon, and other grocery giants.

Kroger 's longtime leader Rodney McMullen abruptly resigned March 2 following a personal conduct probe initiated in February, ending a nearly 50-year career with the Cincinnati-based grocery giant. Here's what we know – and don't – about his career with the nation's largest traditional supermarket chain, and it's sudden end.