Four violent deaths in Wellington were carried out by insane killers, inquests have found.

Wellington coroner Garry Evans has ruled on the deaths of Gavin Dash, Brent Hawkins, Deborah Te Paia and Peter Himona.

Nearly six years after the death of Gavin Dash, 23, Mr Evans has ruled the student was strangled to death by his flatmate David Gates.

Mr Dash, 23, went missing in October 1999 but a homicide investigation was not launched until January 2000.

Nearly five months later Gates led police to Mr Dash's body by drawing a map of the Makara bush area where his severed head and body were found.

Gates was acquitted of murder in September 2001 on the grounds of insanity.

The other killers in cases ruled on by Mr Evans were also found not guilty of murder by reason of insanity.

Brent Hawkins was killed in May 2002 at the hands of his brother, Richard Hawkins, who repeatedly stabbed him in the kitchen of his Paraparaumu home.

Before slashing his brother, Hawkins had been a Capital and Coast Mental Health patient, but was not under any care immediately before the killing.

Diagnosed with schizophrenia and paranoid behaviour, he stopped taking medication after his doctor left Waikanae Medical Centre.

Victor Webby, who also suffered schizophrenia, killed his mother Deborah Te Paia, 54, in November 2001. The inquest found she died from blood loss incurred through stab wounds.

Webby had a long history of mental illness and his family were struggling with his behaviour at the time of the killing.

Lower Hutt student Peter Himona, 39, was also stabbed to death, in February last year, by a schizophrenic killer, John Holthouse, who stabbed Mr Himona while he was resting at the killer's flat.

Despite being under psychiatric care, Holthouse was able to "mask" his psychotic symptoms, passing a number of assessments undetected.

- NZPA