If the systems were correctly installed but failed because someone
"tampered" with them or neglected them, then we're talking about Manslaughter (or Bodily Harm) by Negligence, or even arson by negligence. Who bears responsibility under the
law?
In Businesses: The Legal Representative, CEO, or Employer.
The law makes them absolutely responsible for the safety of employees and
customers. If the emergency exit was padlocked "to keep out thieves," the
Employer will face the most serious charges.
In Apartment Buildings: The Building Manager! Yes, the unfortunate tenant who "reluctantly" took over the common
charges has legal liability. If the building has a fire detection
system and the manager turned it off because "it kept going off for no
reason," or if they let the corridor extinguishers expire three years
ago and someone gets trapped, the manager is considered legally
liable.
In Rentals (AirBnb etc.): The Owner must ensure that smoke
detectors work, extinguishers are serviced and escape routes are clear.