He criticised the handling of a lack of a prosecution of "at least one obvious charge", being careless driving causing death.
"That is a serious failure," Mr Raymond said.
He also criticised police for failing to "act in a timely manner".
Careless driving charges have to be laid within six months of an accident occurring.
Coroner David Crerar is asking police to conduct further investigations.
He says further questions need answering. In adjourning the inquest, the coroner reserved his findings, which he indicated would be released by Christmas.
Earlier, the inquest heard from family members who told how Ms Robinson-Winskill was raised to be "very cautious" around vehicles.
Her daughter from an earlier marriage, Phoebe MacRae described Mr Winskill as an "impulsive" socially-inept man prone to angry moods who was "not always aware of his surroundings".
Ms MacRae was adamant the only reason Ms Robinson-Winskill would've been behind the ute - after turning off a hose Mr Winskill was using to fill up his ute's spray tanks - was if she didn't know her husband was going to reverse.
Mr Winskill yesterday said that before he reversed, he told his wife of 10 years: "I'm just going to put it back in the shed."
Ben MacRae, Ms Robinson-Winskill's eldest of three children, earlier told how his mother had planned to leave her husband three times for "various reasons".
The children were kept in the dark about the affair though. But Linda Rae Winskill, Mr Winskill's sister, said that Ms Robinson-Winskill had confided with her about the affair.
"She was pretty angry about it but wanted to work through what happened."
In the weeks after the accident, Mr Winskill told his late wife's sister Julienne Hide that he knew he'd backed into his wife.
Mrs Hide now struggles with the fact that he then drove forward - running over her again.
She also raised concerns over his interest in other women after the accident, believing that he was relieved that his wife was gone and was now "free of her, of any restraint".
A long-time friend of Ms Robinson-Winskill, LaDene Neumayer claimed that Mr Winskill had been "checking me out" at his own wedding.
She again found him "sleazy" at his wife's funeral, and "a bit upbeat for my liking".
Ms Neumayer personally suspected that Mr Winskill had deliberately tried to kill his wife.
The inquest also heard from a woman who met Mr Winskill on dating website Match.com just weeks after his wife's death.
The woman, whose identity is suppressed, said Mr Winskill's "vain" profile claimed he was a "well-off entrepreneur" who lived at a "magnificent lifestyle block" and had just been widowed after a "tragic accident".
They went on several dates. She found him to be a "narcissistic ... show off" prone to crying over his wife's death, though she wondered whether the tears were "all an act".
When they socialised with his friends and family, she felt "uncomfortable" and soon broke the relationship off.