A 65-year-old man who harboured a “shocking secret” for three decades has been sentenced to 31 years’ jail for murder and rape over a series of attacks on couples at a Melbourne park in the 1980s.

Last year, James Patrick Dobbie pleaded guilty to the 1983 murder of Rodney Mitchell, who was shot at a park in Dandenong North, in Melbourne’s south-east, while in his car with his lover.

The court heard Mr Mitchell was partially undressed when he tried to take the gun off Dobbie in May 1983 and died instantly after two shots were fired.

Mr Mitchell’s female companion – known to the court as KL to protect her identity – was then taken away by Dobbie in Mr Mitchell’s car.

She suffered multiple injuries at the time when she escaped from the car.

Dobbie also pleaded guilty to eight other charges – rape, indecent assault and false imprisonment – over two other incidents involving other couples at the same park in March 1980 and April 1983.

In sentencing, Justice John Champion spoke of the “trail of destruction” Dobbie had left behind him when he “acted to conceal the truth”.

“Your appalling offending left each victim with lifelong trauma,” he said.

“Tragically [Mr Mitchell] paid the ultimate price in confronting you.”

Justice Champion described Dobbie’s offending as “deliberate” and “calculated” and said he had delayed justice by absconding from Victoria.

“You fled interstate and started a new life,” he said.

“You have accepted responsibility and are remorseful, although this has taken decades to evolve to the point of confession.”

The search at the Police Paddocks. Photo: ABC

‘So close … he could smell the gunpowder’

The court heard Dobbie used the same methods in each attack.

He would wait 20 or 30 minutes after a couple had arrived at the Police Paddocks, and they were engaged in “intimate” activity.

“You put the gun through the car window, using the weapon to invoke terror,” Justice Champion said.

In the April 1983 incident, Justice Champion said the gun pointed at the 20-year-old man – known to the court as EF – was “so close that he could smell the gunpowder”.

The woman in that case – known as GH and aged 18 at the time – was raped several times at gunpoint.

The court heard Dobbie’s family had only discovered his crimes in June last year after he confessed and turned himself in to NSW police.

“You harboured a shocking secret,” Justice Champion told him.

“You were not the man they thought they knew and loved.”

Dobbie must serve a minimum 25-year term.

-ABC