A Key Largo firefighter who came close to death trying in vain to save three underground utility workers felled by noxious fumes beneath a neighborhood street last January is suing those men’s employers for negligence. Leonardo Moreno, 32, an eight-year veteran of the Key Largo Volunteer Fire Department, did not hesitate before descending 15 feet into a manhole on Long Key Road in the Lake Surprise Estates subdivision Jan. 16 to save what he was told was one man drowning.