BROOKLN PARK, Minn. — The pilot of a light plane that crashed near Crystal Airport was a retired Mayo Clinic doctor, authorities said. Joseph Ralph Cass, age 73, died apparently on impact. So did his passenger, Liz Comny, a North Dakota state legislator. Cass spent much of his retirement Up North near the resort town of Nevis. The cause of the crash was not identified immediately. Federal investigators usually issue preliminary conclusions within 30 days.
