Two people have been arrested on suspicion of manslaughter after four Vietnamese nationals are thought to have died in a mill fire.
Teams have been searching the building at Bismark House Mill, on Bower Street in Oldham, since demolition workers discovered human remains in July.
They have since found remains of four people.
Greater Manchester Police say it has now arrested two people on suspicion of manslaughter and drugs and organised crime offences after executing warrants at two properties.
The pair remain in custody for questioning.
Detective Chief Inspector Gareth Davies, of GMP’s Major Incident Team, said: "These arrests are part of our enquiries to establish why Uoc and three other, currently unidentified, individuals were in the mill during the fire.
"We are making progress but our investigation is very much ongoing."
31-year-old Uoc Van Nguyen is so far the only person to be identified - with Cuong Van Chu, 39, Duong Van Nguyen, 29, and 21-year-old Nam Thanh Le still unaccounted for.
Mr Nguyen's remains were discovered on 28 July - five days after a first set of human remains were discovered by demolition workers at the mill.
Specialist officers were able to obtain fingerprints from Mr Nguyen's body which matched with an immigration and asylum database.
At the time of the blaze, on 7 May, which took four days to extinguish, no-one was thought to have been inside the building.
Detective Chief Inspector Davies added: "Our thoughts remain with the families in Vietnam. They are being fully updated and supported by specially-trained officers, as we try to find the answers we need and they deserve.
Anyone with information should contact Greater Manchester Police via 101. In an emergency, always dial 999.
International callers can contact GMP via +441618725050. Information can also be submitted in English or Vietnamese via the Major Incident Public Portal: Public Portal.
Anyone who would like to remain anonymous can share information via the independent charity – Crimestoppers on 0800 555 111.