Fernandez said investigation conducted by the Manila Fire Department and Immigration officials confirmed their initial report that the fire started from the office of Executive Director Roy Almoro at the second floor.
He said fire investigators pointed to an outlet where two computer units of Almoros staff were plugged as the source of the two-hour blaze.
"We already submitted the results of the investigation to the National Bureau of Investigation for further verification. Meanwhile, we will be working on the reconstruction of the damaged offices," he said in an interview.
Fernandez discounted the possibility of arson or intentional burning of the BI main office. "We cant think of a good reason why anyone would try to sabotage the bureau, especially Director Almoros office," he said.
The fire, which gutted at least P2 million worth of properties, affected the offices of the Board of Special Inquiry, the Intelligence Office and the Foreign Section Laboratory.
The Immigration official also reiterated that no vital documents, specially those of former Elections Commissioner Virgilio Garcillano, were lost or affected by the incident. "His (Garcillano) files are with the Watch List Department. All the papers there are intact."