I know it's being wise after the event, but some mistakes criminals make seem very obvious.
Whomes & Steele could have just committed the massacre themselves. They wouldn't grass on each other as they both fired the shots.
The police were at a dead end until Nicolls became a supergrass.
Nicholls had just driven them near to the location and then picked them up somewhere else after the massacre. So could afford to become a grass if it benefitted him.
Whomes could have just driven near to the massacre location himself. Then him & Steele walk back to car after carrying out the massacre.
