Judge in Nidal Hasan court-martial bans items related to al Qaeda NEW: The judge again advises Nidal Hasan not to be his own attorney The judge says she doesn't want a mini-trial on another military shooter She also excludes e-mails between Nidal Hasan and a key al Qaeda member Prosecutors hope to show that Hasan had undergone a "progressive radicalization" Fort Hood, Texas (CNN) -- A military judge on Monday excluded e-mails between an Army psychiatrist and a key member of al Qaeda in the Arabian Peninsula from being used in the psychiatrist's death penalty case, evidence the prosecution contends goes to the heart of the motive of the shooting rampage at Fort Hood that left 13 people dead. The judge, Col. Tara Osborn, also refused to allow prosecutors to use materials they maintain show Maj. Nidal Hasan's interest in the actions of Army Sgt. Hasan Akbar, the American soldier sentenced to death for killing two soldiers and wounding more than a dozen others at the start of the Iraq war -- an attack he said he carried out to stop soldiers from killing Muslims. "The court believes Sgt. Akbar is not on trial in this case," Osborn said. "It would only open the door to a mini-trial" and confuse the issue. The rulings came at the start of the third week of the court-martial of Hasan, who is defending himself against 13 counts of murder and 32 counts of attempted murder in connection with the November 5, 2009, attack. It's unlikely the rulings will have impact on the court-martial, as Hasan has left no doubt about his role, telling a panel of 13 officers during a brief opening statement: "The evidence will clearly show that I am the shooter." While the military has avoided labeling Hasan as a terrorist or charging him as such, prosecutors wanted to use the evidence to show that the devout Muslim had undergone a "progressive radicalization," going so far as to give academic presentations in defense of suicide bombings. Hasan, who was scheduled to deploy to Afghanistan, did not want to fight against other Muslims and believed "that he had a jihad duty to kill as many soldiers as possible," lead prosecutor Col. Michael Mulligan has said. Investigations after the shooting rampage found Hasan had been communicating via e-mail with Anwar al-Awlaki, the U.S. born cleric who officials say became a key member of al Qaeda in the Arabian Peninsula. Osborn ruled that the e-mails would have to be "redacted to prevent undue prejudice by association" and would diminish its use as evidence. Along with the e-mails and the material related to Akbar, Osborn also declined to allow the use of Hasan's academic presentation on suicide bombings, saying "motive is not an element of the crime." The judge previously ruled that prosecutors may use evidence of Hasan's Internet searches on jihad and the Taliban in the days and hours before the attack. With the prosecution expected to rest this week, the big question is whether Hasan will take the stand. The judge on Monday raised concerns about Hasan acting as his own attorney after he admitted last week he did not understand that by listing someone as a witness he gave up the right of privileged communication with that person. Remember when I told you that I thought you would be better off with a trained lawyer? Osborn asked. Hasan responded: "Repeatedly." I've advised you before and I'm advising you again that it's not a good policy to represent yourself. ... Do you understand that? Osborn said. Hasan said: "Yes, I do." As he has done with all the prosecution witnesses so far, Hasan declined Monday to cross-examine a forensic expert who testified about weapons used in the shooting inside the Soldier Readiness Processing Center as soldiers and civilians prepared to leave for Afghanistan and Iraq. Much has been made about Hasan's defense or, as his stand-by attorneys have said, the lack of it, indicating he is perhaps more eager to prove he is a martyr than to avoid a death sentence. Hasan refused to enter a plea at the outset of the court-martial after the judge barred him from pleading guilty. Last week, Hasan released a portion of his mental health evaluation to The New York Times. It revealed he believes that being put to death would allow him to become a martyr. Hasan has been confined to a wheelchair since being shot by Fort Hood police to end the shooting rampage. The release of the documents, coupled with Hasan's lack of an appearance of a defense, prompted the military attorneys ordered to act as his stand-by counsel to demand they be allowed to drop out of the case. The judge refused to grant the request, and the defense attorneys have appealed her ruling. In 2006, he inquired about the possibility of filing conscientious objector status. He did not go through with it, and the judge ruled that it could not be used by prosecutors to show motive.