Chemical manufacturer 3M is allegedly hiding files that could shed light on the role that former 3M Chief Executive Officer and Chairman Lewis Lehr played years ago as the company was struggling internally to figure out how to deal with growing evidence that its toxic chemical compound PFOS was widespread in the blood of the general U.S. population.

According to a motion to compel filed Feb. 15 with the U.S. District Court in South Carolina by plaintiffs lawyers in sweeping multidistrict litigation, 3M has repeatedly failed to turn over Lehr’s files to the plaintiffs legal team despite multiple requests as part of court-ordered discovery.

Lehr “played a central role in business decisions related to investigating and reporting potential effects” associated with 3M’s PFOS products, the motion states. Lehr was CEO of 3M from 1979 to 1986 and was a member of its board of directors from 1974 to 1991.