In May 2010, Lamo reported to U.S. Army authorities that then Bradley Manning had claimed to have leaked a large body of classified documents, including 260,000 classified United States diplomatic cables. Lamo stated that Manning also "took credit for leaking" the video footage of the July 12, 2007, Baghdad airstrike, which has since come to be known as the "Collateral Murder" video.
Lamo was criticized by fellow hackers, such as those at the Hackers on Planet Earth conference in 2010, who labeled him a "snitch". Another commented to Lamo, following his speech during a panel discussion, saying: "From my perspective, I see what you have done as treason."
Lamo said in a Wired article that, in May 2010, after he reported the theft of his backpack, an investigating officer noted unusual behavior and placed him under a 72-hour involuntary psychiatric hold, which was extended to a nine-day hold. Lamo said he was diagnosed with Asperger syndrome at the psychiatric ward.