CHARLESTON (AP) — Federal investigators say they can’t determine how a foreman for coal producer Consol Energy fell into the Ohio River in northern West Virginia and drowned late last year.

The U.S. Mine Safety and Health Administration says a lack of conclusive evidence made it impossible to figure out what happened to Mark McIntyre. The veteran foreman was inspecting barges by himself at the processing plant for Consol’s McElroy Mine in Marshall County on Dec. 30.

MSHA says in a report released Friday that it cited Consol for failing to train McIntyre and other prep plant workers about hazards unique to barges.

A spokesman for Can-onsburg, Pa.-based Consol declined to comment.

MSHA says Consol has begun using a new training program for the facility.