Twelve people arrested over a fire in Warwickshire in 2007 which claimed the lives of four firefighters have had their bail extended.
The 12, who include fire service staff, were arrested over the Atherstone fire between February and May 2010.
Their bail was extended after the Crown Prosecution Service told police it needed more time to make a decision on its review of the investigation.
Warwickshire Police has said it is disappointed with the delay.
Det Supt Ken Lawrence said the force's evidence was given to the CPS in August last year.
"Whilst we are disappointed with this delay we appreciate that this has been a substantial investigation and the CPS needs to be absolutely sure of the facts before making its decision," he said.
"The CPS has provided me with a full explanation of the current position which I have shared with the families of the deceased firefighters."
The warehouse fire took place in November 2007.
The bodies of Ashley Stephens, 20, John Averis, 27, and Darren Yates-Badley, 24, were found in the charred remains. Ian Reid, 44, died later in hospital.
Ten of the arrested people were questioned on suspicion of gross negligence manslaughter and two on suspicion of misconduct in a public office.