Police were called to a Glenmore Park home late on February 6, 2010, where they found Mr Strangio dying from gunshot wounds.
Strike Force Goodier was established to investigate who killed the 42-year-old father.
Homicide Squad Commander, Detective Acting Superintendent Virginia Gorman is hoping the reward will prompt anyone with information to come forward.
"Our detectives haven't – and won't – give up on finding those responsible for Mr Strangio's untimely death," Det Supt Gorman said on Monday.
"The public are reminded that there is no piece of information too small for investigators, your tip could be the missing piece of the puzzle in this investigation."
Mr Strangio's brother, Julian Strangio, said he hoped the reward would help bring those responsible to account.
"Paul was a loving father and much-loved member of our family, who didn't deserve what happened to him," he said.
"After 13 years, we're hoping this incentive will encourage people to come forward with the information detectives need to ultimately find justice for Paul."
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