Mr McDonald, who was also a police officer, told the ABC, "It's investigation 101,"
"That's what police do and it's appalling that it was never done.”
He recounted the last phone conversation he had with his wife.
"She said I can't go on any more. I'm not getting better. I'm such a burden…" he said.
"And I said: 'You can't do this'. I pleaded with her and begged her not to.
"She said I love you and the kids. We talked about all the things we'd done together, but nothing I said would make sense to her, she was just that determined to do it".
The N.S.W. Police told the ABC they continue "to improve its practices and procedures, having made significant advances over many years to minimise the psychological impact of policing duties on our officers, who frequently undertake stressful and difficult work," the statement said.
"It is well understood that every officer's circumstances are unique and most often extremely complex with regard to the impacts of psychological injury.”