Forensic police struggled to take control of the scene of Colin Winchester’s murder, eventually locking down the area two-and-a-half hours after the shooting, a court has heard.
"That is no small matter in a murder investigation," George Georgiou, SC, said in closing submissions.
The defence barrister said, by the time the area had been cleared, the crime scene had been "highly compromised".
David Harold Eastman, 73, has pleaded not guilty to twice shooting the police chief at close range as he got out of his car in Deakin about 9.15pm on January 10, 1989.
Mr Georgiou spent his first full day of defence closing submissions examining evidence of witnesses in close proximity to the shooting and the crime scene examination.
The silk described a scene of "chaos" when acting superintendent of the forensic services division, Peter Nelipa, arrived in Deakin about 9.50pm to find numerous police officers in the street and two senior police officers on the grassed strip near driver's side door.
There was an ambulance parked on the driveway, and a number of police cars parked in the street.
Mr Georgiou said there had lack of respect and adherence to crime scene preservation, probably due to the fact the ACT's most senior police officer had been shot.
"[They] wanted to see for themselves," he said.
He said an emotional response was understandable, however, the failure to protect the crime scene, according to police protocol, led to questions of potential contamination or destruction of evidence.
The silk speculated that hair or fibres could have attached themselves to a shoe and be walked out of the area.
"There is a gap ... that is the opportunity to gather evidence from a crime scene that has properly preserved. That opportunity has been lost," Mr Georgiou said
"If you accept there is a gap in the evidence, it is not a gap that can be filled with speculation and guesswork.
"Nothing changes the fact is was not preserved according to fundamental crime scene principles."
The barrister said the jury, in light of that information, are entitled to say: "This is highly unsatisfactory. It is not good enough."
The trial continues.