NEARLY five years after Diana Lesley Matthews was found murdered in a man-made lake in Baldivis, those responsible are now behind bars.
Appearing at the Supreme Court on December 21, Allan Bradley MacIntosh was sentenced to a 20-year minimum term for the murder of Ms Matthews in 2011.
MacIntosh and co-offender Rebecca Anne Hall had planned to steal from Ms Matthews after meeting her to buy drugs at a Baldivis park on April 29, 2011.
Hall was sentenced on April 16, 2015 at the Supreme Court to 11 years imprisonment for murder.
Justice Lindy Frances Jenkins said MacIntosh “had intentionally attacked Ms Matthews in a brutal manner” in an unprovoked attack.
“When you thought that Ms Matthews was dead, you then put her into the reservoir with the help of Ms Hall,” she said.
“You destroyed or stole her belongings so as to conceal her death and your involvement in it.
“You then lied repeatedly to the police. There really is little that can be said in mitigation of the offence itself.”
After meeting Ms Matthews and discovering she had a sum of cash and drugs on her, the pair organised to meet her again later and rob her using violence if necessary.
Hall invented a story resulting in Ms Matthews going with them in Hall’s van.
Hall told police she had second thoughts but did nothing to change the plan except shake her head at MacIntosh.
While driving along, MacIntosh reached forward and strangled Ms Matthews with what was believed to be a piece of wire.
The pair dumped her body at the man-made lake at the Rockingham Regional Memorial Park.
MacIntosh took many measures to cover his tracks by burning evidence and consequently lying to police.
Medical evidence later showed that Ms Matthews remained alive after the ordeal, although unconscious, and drowned as a result of being in the water.
Justice Jenkins said her death was a direct result of MacIntosh’s attack.
“It does not matter as, on either scenario, your acts in strangling her and putting her in the reservoir substantially caused her death,” she said.
In addressing MacIntosh, Justice Jenkins said Ms Matthews’ murder was becoming a cold case.
“You were charged with murder on September 7, 2013. Prior to your co-offender (Hall) approaching the police, you were a suspect in the offence but the police considered there was insufficient evidence to charge either of you. If Ms Hall had not voluntarily approached the police, it is likely you would not have been charged or convicted of this offence,” she said.
Ms Matthews was found by passers-by about 11.30pm on April 29, 2011, in the man-made lake.
Despite numerous public appeals by police, fresh information seemed to evade them, with the death remaining a mystery for a couple of years.
Ms Hall voluntarily handed herself in to police on September 5, 2013. She admitted her part in the murder and agreed to wear a recording device the next time she was with MacIntosh.
Hall’s co-operation resulted in her lesser sentence and being eligible for parole.
MacIntosh was not given any reduction on his sentence.
Justice Jenkins said his circumstances were vastly different from Hall’s, as he continued to deny involvement in the murder and his intention to harm Ms Matthews, albeit not to murder her, and his prior criminal record. His sentence was backdated to September 7, 2013, the day he first went into custody.