Criticism is being levelled at the health system after yet another case of a mentally unwell person killing someone in Wellington.

The death of a Kilbirnie man this week is at least the sixth where the alleged killer was being treated for mental health problems in the region in the last 15 months.

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Graeme Moyle's brother was killed by a mental health patient in 2007, and he said nothing ever seems to change.

"DHBs say they're going to have an investigation. They come out at the end of it with a redacted report that says the same thing as the previous report and the previous report before that".

Moyle said there needs to be more inpatient beds made available.

"If somebody rocks up to an A and E department with a broken leg or something, you get a bed straight away, an x-ray, and the care required. The same doesn't apply to someone who's having a mental health crisis".