Haider Kadhem, 24, was released on Wednesday after being questioned about “inconsistencies” in his statements.
He was taken from the car in which soundman Waleed Khaled was killed on Sunday by multiple shots to the head and chest while on a news assignment.
Iraqi police said US troops fired on the Reuters team, both Iraqis.
A US military spokesman said their investigation was continuing.
Kadhem suffered superficial wounds from flying fragments.
Khaled, who was driving, was the fourth Reuters journalist killed in Iraq since the US invasion of 2003.
Two are known to have been killed by American fire.
A third was shot dead in Ramadi last November in circumstances for which Reuters is still seeking an explanation from US forces.
Reuters’s cameraman in the city of Ramadi, Ali al-Mashhadani, was arrested by US forces three weeks ago and is being held without charge in Abu Ghraib prison near Baghdad.
A military spokesman said on Wednesday that a joint Iraqi-US tribunal, meeting in secret on Monday, had ordered him to be held indefinitely pending a review within six months.
No accusation has been made public and Mashhadani will be allowed no visits, including from an attorney, for two months.