U.S. prosecutors filed court documents in March seeking to admit evidence into trial that indicates David Passaro allegedly abused his former stepson, Matthew Newman, with a flashlight, similar to the way Passaro is accused of beating the prison detainee, Abdul Wali, in June 2003.
A judge ruled that the Newman's testimony does not show intent in the current assault case and that the testimony could prejudice a jury.
The March motion claimed Newman's testimony would show a pattern of violent behavior in Passaro and would show that Passaro intended to inflict pain upon Wali "as a means of extracting a confession from him."
Passaro, a former Special Forces soldier who worked as a civilian special operations employee at Fort Bragg, is charged with four counts of assault in Afghanistan. Prosecutors have said he beat Wali with his hands, feet and a large flashlight while Wali was interrogated for two days at a U.S. base in Afghanistan.
Wali had turned himself in to U.S. forces, which sought him as a suspect in rocket attacks on the base. He later died in custody.
Passaro, who is the first civilian prosecuted on charges of mistreating a military detainee in the U.S. war on terrorism, has been in and out of jail since his initial arrest in June 2004.
Last year, he was arrested for allegedly assaulting his former girlfriend while he was on house arrest waiting for the prisoner abuse trial to begin. In March, he was released from jail but turned himself in to authorities in April after violating terms of another house arrest.
The case was scheduled to go to trial in April but was continued until Aug. 7. It has been delayed several times since his June 2004 indictment because of security concerns and the handling of classified evidence.