Simplify the following text for a Grade 9 native English-speaking person.
Original: John Allen Muhammad ( December 31 , 1960 -- November 10 , 2009 ) was a convicted American spree killer responsible for ten deaths in the Washington area in 2002 .
Simplified: John Allen Muhammad ( December 31 , 1960 -- November 10 , 2009 ) was a spree killer from the United States .