HELENA, Mont. (AP) — BNSF Railway attorneys are expected to argue before jurors Friday that the railroad should not be held liable for the lung cancer deaths of two former residents of an asbestos-contaminated Montana town, one of the deadliest sites in the federal Superfund pollution program.

Attorneys for the company say the corporate predecessors of the railroad, owned by Warren Buffett’s Berkshire Hathaway conglomerate, didn’t know the vermiculite they hauled over decades from a nearby mine was filled with hazardous microscopic asbestos fibers.

The case in federal civil court over the two deaths is the first of numerous lawsuits against the Texas-based railroad corporation to reach trial over its past operations in Libby, Montana. Current and former residents of the small town near the U.S.-Canada border want BNSF held accountable for its alleged role in asbestos exposure that health officials say has killed several hundred people and sickened thousands.