The photos came from a Defense Department video of Padilla, 36, being escorted from his cell at a South Carolina brig where he was held for 3 1/2 years without being charged. He is shown wearing noise-blocking headphones and blacked-out goggles, the New York Daily News reported Tuesday.
Eugene Fidell, president of the National Institute of Military Justice, told the newspaper he found the images "extremely disturbing" and called it "outrageous government conduct."
Mary Ellen O'Connell, a torture expert at Notre Dame Law School, agreed.
"It looked extraordinarily excessive," O'Connell said. "He's only a suspect -- he hasn't been convicted of anything."
The New York-born Padilla, a convert to Islam, was declared an "enemy combatant" after he was arrested in 2002 and prosecutors alleged he was conspiring to detonate a radioactive "dirty bomb" in a U.S. city. When he was eventually charged in 2005 with conspiring in a minor terrorism case but there was no mention of a dirty bomb in the indictment, the newspaper said.