Protected witness Russell Warren has told the Special Criminal Court that John Gilligan told him to tail Veronica Guerin on the day she was murdered.
Warren also claimed he rang Gilligan after witnessing the murder, when Gilligan warning him not to say a word or the same thing would happen to him.
He said he was John Gilligan's bagman; collecting, sorting and counting thousands of pounds and - on Gilligan's orders - taking the money mainly to a man in Amsterdam, though sometimes travelling to Calais or Dover.
He added he stole the motorbike used in the Veronica Guerin murder: "I didn't steal the bike for that purpose, but John told me to hang onto it as he might need it. On the week of the murder, I was due to go to the continent, but Gilligan told me he needed me.
"I was told to go to Naas courthouse on June 26, 1996, and trail a red Opel," he continued. "A blonde woman, Veronica Guerin was in the car. I'd never heard of her.
"Gilligan was in constant contact, asking me the position of the car all the time. The bike passed me and fired five shots at Veronica Guerin through the window. I was stunned and I rang Gilligan. He asked me if she was dead, and said the same thing would happen to me if I said a word," Warren told the Court.