Simplify the following text for a Grade 8 native English-speaking person.
Original: As of 2010 , the last person to be executed in the gas chamber was German national Walter LaGrand , sentenced to death before 1992 , who was executed in Arizona on March 3 , 1999 .
Simplified: The last person to be executed in the gas chamber in the United States was Walter LaGrand in Arizona in 1999 .