The cause of the blaze which destroyed a historic pier remains a mystery, police said.
Almost a century of history went up in smoke when flames engulfed Fleetwood Pier on the Lancashire coast three days ago.
A Lancashire Police spokeswoman said: "Our investigations have concluded. The forensic investigation has proved inconclusive. The fire is still being treated as unexplained."
Firefighters were unable to save the famous landmark, built in 1910, which is now being demolished. It was rebuilt following a major blaze in 1952.
Fleetwood Pier had fallen into disrepair and been closed for more than 12 months prior to the blaze.
Blackpool businessman and comedian, Mike Simmons, whose stage name is Joey Blower, wanted to build 85 flats on the pier - but faced local opposition.
The police spokeswoman said the fire, which is believed to have started in a disused pizza bar at the front of the pier, was either an accident or started deliberately.
The blaze came just months after a fire which gutted the Grand Pier at Weston-super-Mare in Somerset.
There have been other major fires at piers in Brighton, Southend and elsewhere over the years.
Fleetwood, like many coastal resorts, has suffered decline but the attraction was for many years "the jewel in Fleetwood's crown".
