Simplify the following text for a Grade 4 native English-speaking person.
Original: The 1881 robbery of the Sexton Bank at Riverton was suspected to be the work of Jesse James , but it was soon determined to be the work of the outlaw Poke Wells .
Simplified: The 1881 robbery of the Sexton Bank at Riverton was thought to be the work of Jesse James . It was later found out to be the work of the outlaw Polk Wells .