The murder will make it more difficult to conduct a fair trial of the former dictator because officials working for the prosecution and the defence are both threatened with death.
Saadoun al-Janabi was the lawyer for Awad Hamad al-Bandar, a former judge on Saddam Hussein's Revolutionary Court who stands accused of passing death sentences on people from the Shia town of Dujail, 148 of whom were executed after an attempt to assassinate Saddam in 1983.
The day after proceedings against Saddam were delayed, 10 men dressed in suits and ties arrived in Mr al-Janabi's building in the al-Shaab district of Baghdad saying they were from the Ministry of the Interior. They produced guns, kidnapped him and soon afterwards his body was dumped, with bullet wounds to the head and chest, near the Fardous mosque in the Ur district of Baghdad.
The murder will deepen suspicions among Sunni Arabs and Saddam supporters that they are being targeted. They are already fearful of being hunted by death squads from Shia groups such as the Badr Brigade, the paramilitary arm of the Supreme Council for Islamic Revolution in Iraq (Sciri), the largest party in the National Assembly. But with killings in Baghdad running at around a thousand a month and so many groups prepared to kill enemies, it is unclear why Mr al-Janabi was murdered.
The government will now have to try to extend protection to all those involved in Saddam's trial. A witness-protection programme will be difficult to enforce in Iraq, where so many people are armed and likely to seek revenge. Many Sunnis also believe the Ministry of the Interior, now partly under Sciri's control, operates death squads. They will therefore be wary of asking for or receiving protection from the ministry.
However, a leading Sunni politician has said he will take part in talks aimed at "national reconciliation" in Cairo on 15 November. Saleh Mutlaq agreed with the visiting head of the Arab League, Amr Moussa, to take part in the meeting along with around 80 other Iraqi politicians.
Meanwhile, with four more deaths announced yesterday, the number of US military personnel killed in Iraq has reached 1,992.