Police chiefs have admitted they never expect to catch the arsonists who destroyed the West Pier.
Five years on from the blaze of March 28, 2003, the investigation officially remains open.
But Acting Assistant Chief Constable Graham Cox has told The Argus police are no longer appealing for witnesses.
Mr Cox, a superintendent in Brighton at the time, said: "I think realistically that the chances of ever getting to the bottom of it are very, very small.
"Arson is always difficult to investigate because much of the evidence is destroyed.
"Given it was at sea and on a derelict pier makes it even more difficult - we lacked eyewitness accounts and we lacked forensic evidence."
The news has emerged as The Argus publishes - for the first time - internal reports of the attack compiled by the coastguard, which led the emergency services that day.
The documents detail how lifeboats, helicopters, police, firefighters and fishing boats fought in vain to save the pier.
- Read the documents and find out about plans for the site here.
For an eight-page photo supplement to mark the fifth anniversary of the fire, see The Argus newspaper on Wednesday, March 26.
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