CHARLESTON, W.Va. – The head of a Virginia-based coal company is expected to honor an agreement to testify this month about the nation’s worst coal mine disaster in decades despite his sudden retirement plans, investigators said Saturday.

Massey announced late Friday that Don Blankenship, who has been chairman and chief executive since 2000, will retire effective Dec. 31. The modern-day coal baron, who made millions for investors while turning countless neighbors into enemies over mining’s effects on the environment, has been with the company since 1982 in a variety of roles.

Investigators want to question Blankenship about the April 5 explosion at the Upper Big Branch mine, which killed 29 people.

Unlike other Massey employees, who have refused to speak with investigators, Blankenship, 60, reached an agreement with state investigators to testify on Dec. 14. The interview will be closed to the public.

“My team of investigators need to talk to Mr. Blankenship,” West Virginia mining chief C.A. Phillips said Saturday. “I hope he comes, but he may not.”

Phillips said he doesn’t expect the state’s investigation to change with Blankenship’s departure. Neither does J. Davitt McAteer, who was asked by former Gov. Joe Manchin to conduct a separate investigation into the worst mining accident since 1970.

“The investigation is into the accident and not Mr. Blankenship,” said McAteer, who directed the federal Mine Safety and Health Administration during the Clinton administration.