A judge on the special Iraq tribunal set up to try former President Saddam Hussein has been killed in Baghdad.
The judge and his son were killed outside their house in Baghdad
Barwiz Mahmoud Marwani and his son - who was also working at the tribunal - were gunned down outside their home on Tuesday, police said.
This is the first known murder of any of about 20 judges on the tribunal.
In two separate car bomb attacks on Wednesday, at least 13 people were killed and more than 30 others injured in the Iraqi capital.
Insurgents have targeted anyone associated with the US-backed authorities, in the hope of undermining the interim government.
On Monday a huge car bomb killed 125 people queuing up for state jobs in Hilla, south of Baghdad. It was the worst single such incident since the regime was toppled in 2003.
The judge and his son - also a lawyer - were both shot dead by gunmen as they were leaving their home for work on Tuesday morning in north Baghdad, Iraqi police and security sources say.
"He was working with the tribunal. He was involved in cases including Saddam's," an Iraqi interior ministry spokesman was quoted as saying by Reuters news agency.
The killing came just a day after the tribunal completed its first investigation and referred for trial one of Saddam Hussein's half-brothers, Barzan, for a mass killing in southern Iraq in 1982.
Several other former top Iraqi officials are expected to stand trial.
The work of the tribunal, that was set up in December 2003, has been delayed because of security considerations, Iraqi officials say.
The names of the judges and prosecutors involved are kept secret out of fear for their lives.
Saddam Hussein's lawyer, Ziad al-Khasawneh, said he was unsure when Saddam's trial would start.
"Sometimes we hear after one week, sometimes after one month, sometimes we hear end of 2006. Nobody knows," he told Reuters news agency, adding that his defence team has had no contact with the court.
'Soldiers lifted up into air'
Some reports are suggesting that Judge Marwani may have been killed for personal reasons rather than because of his work with the tribunal, the BBC's Jim Muir in Baghdad says.
In the first car blast in Baghdad on Wednesday morning, at least six people were killed and about 30 injured.
Iraq's police and security forces face almost daily attacks
Police and eyewitnesses said the vehicle was driven towards an army base near the old al-Muthanna airport in the western part of the city, as would-be recruits and soldiers queued up outside it.
"It was a suicide car bomb... As he arrived, he blew himself up. There were two soldiers lifted up into the air and knocked across the street," eyewitness Hussein Mohammed was quoted as saying by the AFP news agency.
There are fears that the death toll will rise.
The old airport is home to US and Iraqi military bases and it has been targeted before.
The second car bomb targeted a convoy of Iraqi soldiers in the south-western part of the city, killing seven of them.