Police and fire investigators say they are unable to determine what caused a two-alarm fire that killed a 56-year-old woman May 1.
After months of investigation by four agencies - the United States Bureau of Alcohol, Tobacco and Firearms, the Oregon State Police, the Oregon State Fire Marshal's Office and the Lake Oswego Fire Department - officials say they know only that the fire at 186 D Ave. began on the first floor.
After an extensive investigation involving interviews and lab work, officials say damage to the lower level of the condo made it difficult to determine a cause.
They say the fire originated in the lower level of the condo and traveled to the upper floor, blocking the escape route for two occupants inside.
Carol Frank, a long-time local resident and a dental hygienist, died in the blaze.
Her son Andrew Frank, then 16, jumped 13 feet from a window on the second floor after waking to find heavy smoke in his room shortly after midnight.
He quickly found a hide-a-key and opened the front door of the home but was blocked from entering by a wall of flames. Fire officials say Frank tried briefly to fight the fire with a garden hose before running to a neighbor's house to call 9-1-1.