The 29-year-old pleaded guilty to gunning down Pcs Nicola Hughes and Fiona Bone on September 18 last year but continues to deny the murders of father and son David and Mark Short.
Preston Crown Court was shown CCTV of the moment Cregan handed himself in to police at Hyde Police station, just minutes after shooting the two officers.
He lured the unarmed women with a bogus 999 call before using a Glock handgun and a military fragmentation grenade to kill them in Hattersley, Greater Manchester.
He denied murdering PC Bone, 32, and PC Hughes, 23, at the start of his trial last week but changed his plea following the lunch adjournment on the fourth day.
Trial judge Mr Justice Holroyde said there were remaining charges against Cregan, who is on trial with nine others, but this new development would change the time-tabling for the trial.
He told the jury: “If you cast your minds back to the very start of the case you will remember that I indicated to you that in due course you will be asked to record separate verdicts on each defendant on each charge that they face
“Looking at it in those terms you have heard of Mr Cregan’s admissions of guilt on these two charges and clearly these pleas do not change the position of the other defendants.”
Jurors were sent home shortly after the development to return this morning, when the trial is set to continue.
Greater Manchester Police said in a statement that they welcomed the guilty plea but could not comment further because of the court proceedings.
The families of the two officers did not attend yesterday’s hearing but last week relatives sobbed in court as they listened to details of the “bloody conclusion” to Cregan’s alleged string of attacks.