The State Medical Examiner's Office has ruled that the death of a 64-year-old New Durham woman, found in her home last Thursday, was accidental and attributed the death to lung disease as well as failure of her oxygen supply. Mary Kay Valley was found dead in her home on Kings Highway early Friday morning after a power outage in the area, the result of a motorist who fell asleep at the wheel and crashed into a utility pole in Milton last Thursday night. Valley worked at Alton Central School and the Governor Wentworth School District for 13 years as a secretary before retiring in 2011.