IDREES ALI, JONATHAN LANDAY and SARAH N. LYNCH A probe into the leak of secret U.S. documents likely will require investigators to examine those who had access and scrutinize details like objects captured in photos of the materials, former U.S. officials told Reuters, as pressure grows to find the person or group responsible. The Department of Justice opened a formal criminal probe last week after the matter was referred by the Pentagon, which is assessing the damage done by what may be the most damaging release of classified U.S. information in years. Reuters has reviewed more than 50 of the documents, labelled "Secret" and…