THE BRONX - The fire marshal who responded to the scene of the deadly 2005 blaze in the Bronx that killed two FDNY firefighters testified before the jury in the ?Black Sunday? trial Wednesday.

Fire Marshal Raymond Ott told the jurors that an illegal partition constructed by tenants on the third floor trapped the fire, creating an overheated fireball that prevented Lt. Curtis Meyran and John Bellew from escaping the building, forcing them to jump to their deaths.

According to Ott, had there been no partition, the firefighters would have had a better chance of surviving the blaze.

Ott also testified that splice wires and faulty electrical outlets sparked the fire inside the third-floor partitioned room.

A defense attorney, however, argued the wiring job was not at fault because a metal bed frame charged the outlet.

Cesar Rios, the building's landlord, and tenants Rafael Castillo and Caridad Coste are facing manslaughter charges for allegedly contributing to the deaths of Meyran and Bellew by erecting illegal partitions.

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