'LOVE/HATE' actor Peter Coonan appeared "unresponsive and detached" moments before he allegedly fled the scene of a road incident, a court heard.
Mr Coonan (28), who plays Fran in the gangland drama, appeared before Dun Laoghaire District Court charged with four road traffic offences.
The star is facing charges arising out of an alleged incident on the N11 in Foxrock on May 22, 2011.
Trevor McNaughton told the court he was driving his Honda motorcycle on the N11 when he noticed a car behind him being driven in a "very erratic" manner.
"I had concerns he was going to cause an accident.
"The next thing I knew I got a jolt from behind. He hit the back again."
He then parked his motorcycle and at that stage Mr Coonan also stopped his car.
Padraic O Giollain, a witness, said of Mr Coonan: "I found him detached, disinterested and unresponsive."
Mr McNaughton told him to stay while he called the gardai.
He told the court that while he was on the phone Mr Coonan drove off.
He pursued the car and noticed the vehicle in a nearby housing estate.
"He was just getting out of the car. He turned and walked over to a wall that divides two housing estates and climbed over it."
Mr Coonan denies the offences. Judge Reilly adjourned the case until May 23.