Dwight Smith of Wilmington was arrested late Monday, The Philadelphia Inquirer reported. He was pulled over because he was driving a red Hummer like the one witnesses saw when Marsha Lee, 65, was abducted earlier Monday as she walked her dog.
Smith's father, also named Dwight, said his son's convoy was bombed in Afghanistan just before he was to return from his second deployment. The father said his son's head was injured.
"He made it back, but for me, I don't think he made it all the way back," he told KYW-TV, Philadelphia.
The killing shocked the neighborhood of Brandywine Hills in Wilmington, where one of the residents is U.S. Sen. Tom Carper. Ellen Casson, a longtime member of the Community Association, said Marsha Lee was "just very committed to the neighborhood."
Smith was based at Fort Drum in upstate New York, his Facebook page stated.