The shooting death of a retired London, Ont., police officer by another officer, who then killed herself, was neither predictable nor preventable, a report has concluded.

Police released a final report Tuesday into the 2007 deaths of Acting Insp. Kelly Johnson and retired superintendent David Lucio. The report, prepared by three civilians from outside the force, followed an internal police probe.

Johnson, 40, and Lucio, 57, were found with gunshot wounds in a crashed minivan last June in downtown London. Lucio had been behind the wheel. Both later died in hospital. Police said Johnson shot Lucio before shooting herself.

The report says the two had recently ended an affair and Johnson was feeling "desperate."

"No professional involved with Kelly Johnson, her friends, family or colleagues had any foresight of the … circumstaces and impending tragedy," said the report, according to the London Free Press.

The Free Press said the two had dated for several months, but that days before their deaths, Lucio had told Johnson he planned to reunite with his wife.

Johnson had served as detective sergeant of the sexual assault and child abuse section, and had received a promotion last week. She was the highest-ranking female officer on the force.

Lucio was a 35-year veteran of the London police force.