A psychiatrist advised police investigating the murder of Colin Winchester to act like an immoveable rock when dealing with the suspect David Eastman, a jury heard Tuesday.
The psychiatrist said the officer's should maintain visible presence and for the lead investigator Richard Ninness to maintain a strong position as head of the investigation.
More details of the extensive police investigation following the police chief's murder emerged on Tuesday as Mr Ninness took the stand for a second day.
The ACT Supreme Court heard how an undercover female police officer had befriended Mr Eastman at a local swimming pool to gain his trust, before they went on a date to the War Memorial.
Mr Ninness and a police colleague approached the pair while at the memorial, and while the colleague pretended to speak to the woman, Mr Ninness questioned Mr Eastman.
He agreed Mr Eastman's lawyer had already sent a letter saying he did not wish to speak to police.
The former cop also agreed under questioning by defence counsel George Georgiou SC that he had hoped Mr Eastman might talk to the undercover female officer and reveal something incriminating.
The court also heard during the cross-examination that Mr Eastman was receiving phone calls from people who would hang up as soon as he answered.
Mr Eastman later found out from Telecom that three of the hang up calls had come from the Civic police station.
Mr Georgiou also suggested to Mr Ninness that he had confronted Mr Eastman on Ainslie Avenue one day as the former public servant was eating ice cream in his car.
Mr Ninness agreed he removed the keys from the ignition and positioned his body close to Mr Eastman, and that the door could not close.
But the former senior officer told the court he could not recall the ice cream, nor opening the car door.
Mr Ninness described Mr Eastman's demeanour at the time as irate. The officer agreed he had become verbally aggressive towards the end of the interaction.
"Shut up for a minute, shut up," Mr Ninness is heard to say on a tape of the incident played to court.
"I'm not obliged to speak to you," Mr Eastman says.
The date of the ice cream incident was March 22, 1989, more than a month after Australian Federal Police Assistant Commissioner Colin Winchester was shot dead in his car in Deakin.
Mr Eastman was one of several suspects police pursued in the investigation to solve the murder.
The former public servant is on trial and has pleaded not guilty to murder.
Mr Ninness agreed under cross-examination by Mr Georgiou that there was surveillance on Mr Eastman's Reid flat 24 hours a day for more than a year.
Mr Georgiou also suggested that police engaged in an orchestrated campaign, in which they would go to Mr Eastman's flat under the ostensible purpose of returning property seized in search warrants.
The former officer agreed that the true motive of the visits was to remind Mr Eastman he was a suspect.
Mr Ninness said Mr Eastman became frustrated with the surveillance. "He was seeking out the surveillance operators and acting very aggressively," he said.
Mr Eastman would pick up stones and throw them at police officers in their cars, he said.
Mr Ninness was also cross-examined on the police investigation into the Italian mafia and it's connection to the death of Mr Winchester.
He also said that within 48 hours of Mr Winchester's death the City police station had received an anonymous phone call saying "Best is next".
He said there was a police officer named Best who had been involved in an operation with Italian organised crime in which officers pretended to be corrupt with the promise of protecting the cannabis crop growers.
But members of the group were later arrested and put before court, the court has heard.
The trial continues.