The Health and Disability Commission says two nurses and a resthome in Canterbury failed to provide adequate care for an elderly man who became humiliated and lost his desire to live.
Deputy commissioner Tania Thomas says the 93-year-old needed hospital-level care at Karadean Court Lifecare in 2008, but it could not provide that and gave him a resthome-level bed.
Ms Thomas said the man's care over the following week was sub-standard, he was left in an unclean state and could not summon help.
The man deteriorated, and soon after died in hospital from septic shock.
A registered nurse knew the man needed round-the-clock care, but failed to ensure that happened, while the nurse who admitted him did not assess him properly.
Ms Thomas said the resthome management could have done a great deal more to support and supervise staff. The resthome's owner, Ultimate Care Group, is also faulted.
Ultimate Care Group chief executive David Renwick said he has apologised to the man's family.
"Certainly, there were complaints and my understanding is they were addressed at the time. That was followed by remedies to the procedure to make sure it could never happen again.
"I have apologised to the family, because I know there must have been a great degree of distress for them. It's certainly something that we never want to see happen again."
Mr Renwick said it is the first time his company has been involved in a full investigation by the Health and Disability Commission.