BRAINTREE, Vt. --An enigma on Flight 923, Catherine Mayo was a mystery in her small Vermont town, too. Mayo, 59, caused a major scare when she passed notes to crew members, urinated on the floor and made cryptic remarks to crew members on the London-to-Washington, D.C., flight. Her attorney, federal public defender Page Kelley, said Mayo was "just barely lucid" when they spoke. "She's got some very serious mental health problems," said Kelley.