A joint investigation into a blaze at the former Victoria Road School in Torry has not taken place due to the building not being safe to enter.
Fire crews and police were called to the disused Aberdeen building at around 9.20am on May 10.
The roof of the former school, which closed in 2008, partly fell in during the incident and there was significant damage.
Detective Inspector Allen Shaw said: “It has not been possible to carry out a joint fire and police investigation at this stage. We are carrying out inquiries to establish the full set of circumstances and would appeal for anyone with information or who saw anything unusual or suspicious around the time of the fire to contact us on 101 using reference number 0793 of Friday, 10 May.
“We are continuing to work closely with our partners, including the Scottish Fire and Rescue Service. There is nothing to suggest any suspicious circumstances however we are keeping an open mind.”