A preliminary investigation identified the explosive as propane, she said.
Previous investigations had identified areas where the insurers' record keeping could be improved.
One investigation identified a Wikipedia editor likely to have written an article about a war that never happened.
Initial investigations at the shopping centre identified a few possible suspects.
An internal investigation subsequently identified 13 students, although two have since been cleared.
The investigation identified eleven causes and contributing factors of the crash in its final report.
The investigation also identified a money-laundering operation worth more than A$9 million.
"Our joint investigation quickly identified those students and staff that would benefit from preventive testing."
Both suspects were arrested but the investigation identified Adams as the trigger man.
An investigation by a criminal court with the help of Spanish police experts identified the killers as three former army or state security officers.