Police have been given more time to question 29-year-old Dale Cregan on suspicion of the murders of PC Fiona Bone and PC Nicola Hughes.
A warrant of further detention was obtained on Wednesday night and is due to expire at 9am on Friday morning.
A 28-year-old man who was arrested on suspicion of conspiracy to commit murder yesterday also remains in police custody
Officers nationwide have offered cover to colleagues in Greater Manchester Police so they can attend the funerals of the two killed PCs.
Manchester's police chief said he expected "developments" in the next 24 hours over possible charges relating to the deaths of two officers.
Over 50,000 tributes have been posted to Greater Manchester Police's online book of condolence to the two killed officers and Facebook page.