Wednesday, May 22, 2013
The 29-year-old had already pleaded guilty to the murders of Manchester PCs Fiona Bone and Nicola Hughes.
Cregan had denied killing Mark Short, 23, in May and his father David, 46, three months later in a gun and grenade attack in a trial at at Preston Crown Court.
He has been on trial, along with eight other men, accused of murdering the Shorts.
On Wednesday morning, he changed his plea to guilty.