The former head of a Long Island, N.Y., company that sold body armor to the U.S. military and to law enforcement agencies was convicted Tuesday of insider trading, fraud and obstruction of justice, bringing to a close a marathon eight-month federal court trial.

An Eastern District jury sitting in Central Islip convicted David H. Brooks, the founder and former CEO of DHB Industries of Westbury, on all 17 charges against him. It also convicted Sandra Hatfield, the company’s former chief operating officer, on 14 of 16 charges.