Denis Donaldson's car was examined today by detectives searching for those responsible for killing the British spy.
As the Taoiseach Bertie Ahern confirmed Garda had no intelligence on the identities of the men involved, the Vauxhall Astra estate was removed to be forensically examined.
Mr Donaldson (56) was seen driving it just before he was gunned down and detectives want to know if anyone else may have been in it around the same time.
Specialists will examine the seats and boot for any fibres that could provide a breakthrough in the murder inquiry. Mr Donaldson, a Sinn Fein official turned agent, was shot dead by a number of shotgun blasts at his son-in-law's cottage near Glenties, Co Donegal.
Garda underwater and dog units have also been drafted in to strengthen the inquiry. Garda Inspector Ray McHugh said tonight: "The scene is still sealed off. There's a very intensive technical examination under way, and the water unit is going to be carrying out searches as well.
"A lot of detectives and uniformed officers are on the ground examining the scene and surrounding areas. It's an extensive trawl."
Mr Donaldson was arrested in October 2002 amid allegations that republicans ran a spy ring at the heart of former Northern Ireland Secretary John Reid's office at Stormont.
But after a three-year legal battle, the Public Prosecution Service dropped the charges against Mr Donaldson, his son-in-law Ciaran Kearney and civil servant William Mackessy last December.
Then in another twist, Mr Donaldson was unmasked as a spy.