The man, in his 50s, was detained yesterday morning under Section 13 of the Non-Fatal Offences Against the Persons Act on suspicion of endangerment.
Gardai confirmed today that he had now been released without charge.
"A file will be prepared and forwarded to the DPP," a Garda spokesman said.
The families of the two firefighters have been campaigning for reform of the fire service in Co Wicklow since the deaths.
They believe there was a delay in responding to the blaze as it was out of control by the time the two firefighters arrived.
Mr Murray, a 10-year veteran of Bray's fire service, had warned superiors just three weeks earlier of dangerous practices in the fire service.
A woman, also believed to be a member of the fire service, was arrested in October, while a man in his 40s was detained in September. Both were released without charge.
An inquest into the men's deaths opened in November last year at Dublin County Coroner's Court and was adjourned until this March to allow the Garda inquiry to continue.
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Written by Senan Hogan