The Air Force is investigating a top official in the Guantnamo war crimes trials following complaints that he inappropriately sought to influence the prosecution of cases. Defense lawyers and human rights groups have accused Air Force Brig. Gen. Thomas Hartmann, who supervised the prosecution of enemy combatants at Guantnamo Bay until he was reassigned last month, of lacking neutrality and pushing for premature prosecutions to rally public support for the tribunals. Air Force Maj. David Frakt, a military defense lawyer who has represented several Guantnamo detainees, said the probe was launched after he and others alerted authorities about possible ethical violations by Hartmann. Frakt said that he informed his superiors in July of concerns regarding Hartmann's unprofessional conduct" and "lack of candor," and that the investigation could result in professional sanctions and might give some detainees grounds to challenge actions that Hartmann took in cases against them. Hartmann was removed as legal adviser for the Guantnamo trials in September. He continues to oversee the tribunals in his new post, but is not directly involved with prosecutors. Military judges have already barred him from participating in three Guantnamo trials, saying he lacked impartiality and aligned himself too closely with prosecutors. The investigation is proof that serious questions remain about the tribunals' fairness, said Jennifer Daskal, a lawyer for Human Rights Watch, which has lobbied on behalf of the detainees. "The Department of Defense has absolutely refused to clean house."