During his time in the secret police, Barzan played a key role in the Iraqi regime's execution of opponents at home and assassinations abroad.

[5] Swiss intelligence services alleged that Barzan controlled the al Tikriti family's vast wealth through the canton of Ticino headquartered firm Mediterranean Enterprises Development Projects (MEDP).

[6] U.S. officials characterized Barzan as a member of what they called "Saddam's Dirty Dozen", responsible for torture and mass murder in Iraq.

According to Indict, a US-backed organisation based in London which advocated for Iraqi war crimes tribunal, he was personally responsible for murdering and torturing scores of innocent people, including the inhabitants of one entire village, while he was head of the secret service.

[13] During the trial one woman testified that after her arrest she was stripped naked and tied up by her feet before the intelligence chief kicked her in the chest repeatedly.

It was alleged that, in addition to the killings, hundreds of women and children from the town were jailed for years in desert internment camps, and that date palm groves, which sustained the local economy and were the families' livelihood, were destroyed.

On 21 October 2005, 36 hours after the first hearing, a group of unidentified armed men dragged one of the defense attorneys from his office in east Baghdad and shot him dead.

The defense lawyers, supported by the Iraqi Bar Association, imposed a boycott on the trial until their security concerns were met with specific measures.

A few days before the trial was to resume, the defense team announced that it had accepted offers of protection from Iraqi and U.S. officials and would appear in court on 28 November 2005.

[16] After a short court session on 28 November 2005, during which some testimony regarding the killings in Dujail was presented, Judge Rizgar Mohammed Amin ordered a one-week adjournment until 5 December, to grant the defense teams time to find new counsel.

In November 2006, Iraqi President Jalal Talabani appealed for Barzan to be moved to medical facilities to receive treatment for his spinal cancer.

Barzan, along with co-defendants Saddam Hussein and the former Chief Justice of the Iraqi Revolutionary Court al-Bandar, were sentenced to death by hanging.

On 15 January, U.S. Secretary of State Condoleezza Rice said in a news conference with the Egyptian foreign minister:[21] "We were disappointed there was not greater dignity given to the accused under these circumstances."