Washington ? Marines in Iraq conducted mock executions of juvenile prisoners last year, burned and tortured other detainees with electrical shocks, and warned a Navy medic they would kill him if he treated any injured Iraqis, according to military documents made public Tuesday.

The latest revelations of prisoner abuse, obtained by the American Civil Liberties Union in a lawsuit against the government, involved previously unknown incidents in which 11 Marines were punished for abusing detainees. Military officials indicated that they investigated 13 other cases but deemed them unsubstantiated. Military superiors handed down sentences of up to a year in confinement after finding Marines guilty of offenses ranging from assault to “cruelty and mistreatment.”

The new documents are the latest in a series of reports, e-mails and other records that the ACLU has obtained to bolster its contention that the abuse of prisoners goes far beyond the handful of soldiers charged with abusing detainees at Abu Ghraib.

The mistreatment occurred as early as May 2003, months before the first allegations of abuse at the Abu Ghraib prison were recorded. And the most recent case involving prisoner abuse by the Marines occurred in June.

Anthony D. Romero, executive director of the ACLU in New York, laid responsibility for the abuse at the Pentagon. “This kind of widespread abuse could not have taken place without a leadership failure of the highest order,” he said.

The documents described Navy criminal investigators scrambling to keep pace in June with an “exploding” number of abuse cases.

In all, some three dozen prisoners in Iraq and Afghanistan are believed to have died in U.S. custody. The cases are in various stages of investigation or prosecution.

In the case that drew the stiffest punishment, a one-year prison sentence for the Marine, a detainee at Al Mahmudiya was shocked with an electric transformer. Wires were held against his shoulders and “the detainee danced as he was shocked,” the documents state. The new records, which blacked out the names of soldiers, also show that a Marine was convicted of ordering four juvenile Iraqi looters to kneel down beside two shallow holes in Adiwaniyah. Then, “a pistol was discharged to conduct a mock execution.”

A detainee in Al Mumudiyah suffered second degree burns and blisters on the back of his hands when “a Marine guard squirted alcohol-based sanitizer” on him. A match was lighted, igniting the prisoner.