Many details of the investigation - dubbed Operation Canvas - have been covered by a wide-reaching suppression order.
All that can be said is that covert operatives gained Reddy's trust over six months through their participation together in staged criminal activities.
It was the first time a jury in this country had heard extensive details of such a case.
At the end of that operation, the defendant confessed to killing the victims and unwittingly led officers to spot on the North Shore where he had buried the bodies.
Reddy argued at trial that the murders had actually been committed by a part-Indian man named James who was seeing Ms Yusuf around the time of her disappearance.
But he gave little more than a vague description of his appearance and did not know his surname.
He said his only role was to suggest to James where the bodies could be buried, which was how he was able to lead undercover officers to the grave site.
The jury roundly rejected that explanation and Reddy was unanimously found guilty on both counts after half a day's deliberation.
Justice Asher reserved his decision on today's hearing.