SAN FRANCISCO — Dimitrios Biller and Samuel Wilner drove 3 1/2 hours from Dallas to Marshall, Texas, on the warm last day of September, carrying four banker’s boxes of documents that could prove that Toyota hid evidence in death and injury accident cases.

Biller had organized the documents chronologically, packing them in the Toyota boxes he’d been given to take his stuff when he left the company’s legal department two years ago. He flew with Wilner, an old friend and fellow lawyer, from his home in Los Angeles to personally deliver the boxes to the federal courthouse in Marshall.