Warwickshire Police's search and rescue operation at the site of a devastating fire in Leamington is expected to start on Monday (September 27).
The incident took place at Leeson Polyurethanes in Hermes Close one month ago on August 27.
The blaze engulfed the whole building and one employee, David Boswell, 52, from Leamington, who was working at the site at the time of the fire, remains unaccounted for and is presumed to be dead.
The search for David has been delayed while fire service staff, structural engineers and demolition experts took steps to make the site safe.
Warwickshire Police have said: "This was a long and complex procedure requiring a significant multi-agency response due to the devastation of the site and the presence of volatile chemicals that were stored in the building.
"The primary police priority will now be to recover David as soon as is practicable.
"Recovery and recording of evidence will also ensue so that the cause of the fire can be determined.
"Specialist machinery and equipment will be bought in to assist the operations, minimising manual handling and disturbance of debris.
"A police presence at the site will remain until the operations are complete."
Det Supt Jon Marsden said: “We are relieved to finally be able to access the site to begin our search. The delay has been unfortunate and distressing for David’s loved ones and we are grateful for their understanding.
"Due to the challenging conditions we are dealing with, this will be a very complicated operation involving a meticulous examination of dust and debris which may unfortunately take yet more time.
"David’s family will be kept informed every step of the way by the officers who are supporting them through this difficult time."