They span almost 40 years and collectively illustrate the darkest multiple-murder mysteries in the Hunter’s history.
But the deaths of two young lovers, a middle-aged couple and a pair of misfit drug users may have more in common than being still-unsolved double homicides.
Similar questions remain. Did the killer initially only target one of the victims? Was the second victim collateral damage? Were they just in the wrong place at the wrong time?
There is evidence which points to such scenarios – like the fact that Susan Kay just happened to be at her friend Joanne Teterin’s home when the small-time drug dealer opened the door one May morning and let their killer inside.
Investigators are certain Ms Teterin knew her killer. They believe that, as was usual for drug buys, her killer rang from a nearby pay phone at Carrington before knocking on the Doran Street cottage door on May 11, 2000.
He savagely attacked Ms Teterin but police have always believed it was only after he had already murdered her that the killer realised he was still not alone.
Ms Kay, a some time prostitute and heroin addict, was found dead in a bed in another room.
The evidence points to her being asleep when her friend was attacked and before she was bludgeoned.
The women’s bodies lay undiscovered for five days, meaning crucial evidence may have been lost. It gave the killer enough of a head start for the trail to run cold.
Police believe a drug buyer was responsible, and that the buyer did not know that Ms Kay had decided to visit Carrington the evening before and bunk down for the night.
Her death, investigators have always believed, occurred only because she was there.
The same appears to ring true for the bashing of middle-aged Caves Beach couple Robert Pashkuss and Stacey McMaugh in 2008.
Homicide investigators believe the killer was after Mr Pashkuss, who was known to dabble in very small-time drug dealing around the seaside suburb.
He dealt mainly in small amounts of cannabis, sometimes amphetamines, prompting police to theorise the deaths were either drug-related or a personal vendetta against him.
But investigators are adamant Ms McMaugh, who was well known for her volunteer and charity work, was a completely innocent party.
The murderer entered the couple’s home between 9.50pm on January 5 and early the following morning, and bashed Mr Pashkuss so viciously that fingerprints were needed to formally identify him.
With the same weapon, probably a metal bar 30 to 40centimetres long, the killer then murdered Ms McMaugh as she slept.
Although it is clear in the Carrington and Caves Beach murders that the second victim was killed as an afterthought, it is not so clear who wanted two young lovers dead 40 years ago, attacking them as they embraced on a balmy summer night.
Nurse Irene ‘‘Alex’’ Rees, 19, and her boyfriend of three months, Raymond Hill, 24, had been to the drive-in before parking near South Newcastle Beach pavilion after midnight.
They were popular youngsters and Ms Rees had obtained a late-night leave pass to stay out after the curfew at the nearby nurses’ quarters.
They were in a passionate embrace when a gunman shot them through an open window of Mr Hill’s Valiant about 1.10am.
It is now widely accepted that the gunman had parked next to the couple before blasting three shots into the vehicle, striking Mr Hill before taking aim at Ms Rees.
But it will never be known for sure. The fact that they were not found dead for four hours put police on the back foot immediately.
By the time a university student parked next to the Valient and made the gruesome find, council workers had been and gone.
With them went any ballistic evidence from the murder weapon. No casings, nothing, was recovered.
So who was the killer? Despite stories of maniacs running rampant through the Hunter at the time, most involved in the 1970 case do not believe the murders were random.
A couple parked in a popular spot when a gunman with death on his mind happens across them? Not likely.
The hunch was always that it was someone with a grievance, maybe a jilted lover.
Was he simply following the couple after they watched It’s a Mad, Mad, Mad, Mad World at Lambton’s Skyline drive-in before jealous rage took over?
Was he angry with one and not the other? Did he kill both because they would have recognised him? Why did he shoot Mr Hill before the girl? Who was he really after?
Unless a future forensic advancement picks up something not known today, it seems no one will ever know.