Those who have seen the photos say they are grisly: soldiers beside newly killed bodies, decaying corpses and severed fingers.
The dozens of photos, described in interviews and in e-mails and military documents obtained by The Associated Press, were seized by Army investigators and are a crucial part of the case against five soldiers accused of killing three Afghan civilians earlier this year.
Troops allegedly shared the photos by e-mail and thumb drive like electronic trading cards. Now 60 to 70 of them are being kept tightly shielded from the public and even defense attorneys because of fears they could wind up in the news media and provoke anti-American violence.
"We're in a powder-keg situation here," said Eugene R. Fidell, president of the National Institute for Military Justice and a military law professor at Yale University.
Since the images are not classified, "I think they have to be released if they're going to be evidence in open court in a criminal prosecution," he said.
Maj. Kathleen Turner, a spokeswoman for Joint Base Lewis-McChord near Seattle, where the accused soldiers are stationed, acknowledged that the images were "highly sensitive, and that's why that protective order was put in place."
She declined to comment further.
At least some of the photos pertain to those killings. Others may have been of insurgents killed in battle, and some may have been taken as part of a military effort to document those killed, according to lawyers involved in the case.
Among the most gruesome allegations is that some of the soldiers kept fingers from the bodies of Afghans they killed as war trophies. The troops also are accused of passing around photos of the dead and of the fingers.
Four members of the unit — two of whom are also charged in the killings — have been accused of wrongfully possessing images of human casualties, and another is charged with trying to impede an investigation by having someone erase incriminating evidence from a computer hard drive.
"Everyone would share the photographs," one of the defendants, Cpl. Jeremy Morlock, told investigators. "They were of every guy we ever killed in Afghanistan."
After the first slaying, one service member sent urgent e-mails to his father warning that more bloodshed was on the way. The father told the AP he pleaded for help from the military, but authorities took no action. A spokesman said Friday that the Army was investigating.
The graphic nature of the images recalled famous photos that emerged in 2004 from the Abu Ghraib prison in Iraq. Those pictures — showing smiling soldiers posing with naked, tortured or dead detainees, sometimes giving a thumbs-up — stirred outrage against the United States at a critical juncture. The photos were a major embarrassment to the American military in an increasingly unpopular and bloody war.
In a chilling videotaped interview with investigators, Morlock talked about hurling a grenade at a civilian as a sergeant discussed the need to "wax this guy."
Morlock's attorney, Michael Waddington, said the photos was not just shared among the defendants or even their platoon. He cited witnesses who told him that many at Forward Operating Base Ramrod in Kandahar Province kept such images, including one photograph of someone holding up a decapitated head blown off in an explosion.
That photo had nothing to do with Morlock, he said. It's not clear whether it's among the photos seized in the case.
On Sept. 9, Army prosecutors gave a military representative of the defendants, Maj. Benjamin K. Grimes, packets containing more than 1,000 pages of documents in the case. Included were three photographs, each of a different soldier lifting the head of a dead Afghan, according to an e-mail Grimes sent to defense lawyers.
Later that day, before the documents could be shared with the defense lawyers, the prosecutors returned to Grimes' office and demanded to have the packets back, Grimes wrote, according to a copy of the e-mail first reported by The New York Times.
The prosecutors cited national security interests and a concern that the photos could be released to the media.
Grimes said his staff initially refused to return the photos, but the next day, the Army commander at Lewis-McChord who convened the criminal proceedings, Col. Barry Huggins, ordered them to do so. They complied.
At a preliminary hearing in Morlock's case Monday, Army officials confirmed that the number of restricted photos is 60 to 70. The investigating officer said he would view the photos in private.
Defense attorneys will also be allowed to see them if they visit the criminal investigations office on base, but they cannot have copies — an arrangement that did not satisfy Grimes. The defendants have been detained and cannot travel to see the photos to assist in their own defense, he noted, and most of the defense lawyers are based out of state.
Michael T. Corgan, a Vietnam veteran who teaches international relations at Boston University, said it should be no surprise that, even after Abu Ghraib, some soldiers take gruesome pictures as war souvenirs.
"They're proof people are as tough as they say they are," Corgan said. "War is the one lyric experience in their lives — by comparison every else is punching a time clock. They revel in it, and they collect memories of it."