Charges have been laid in relation to all the deaths apart from that of a 3-month-old baby girl who died in Porirua in November. But a man has been charged with an unrelated assault on the baby.
Cotter said the district was still averaging 4.5 murders a year which had remained unchanged for more than 20 years.
"However, having any homicides is a tragedy because not only has somebody died but it affects their family and the wider community so any homicide is one too many," he said.
Police resources appear to be handling the number of homicides well - the Wellington district has even been lending a hand with policing in Northland, Bay of Plenty and Whanganui.
"So not only have we been able to deal with the homicides that have occurred within the Wellington district, but we've been able to support other districts who have also had pressure on their resources," Cotter said.
Three of the eight homicides this year happened in Lower Hutt.
Hutt South MP Chris Bishop said residents were concerned but they backed police.
"I know they've been working really hard. I meet with them regularly, and they're getting to the bottom of some pretty tragic circumstances."
Bishop said the man who died in the incident at Petone was an acquaintance of his.
"He was a very community-minded person down that end of Petone. My heart just goes out to his family and whanau."
He said the community in Petone would be struggling at this time.
While police have taken swift action putting someone before the courts in relation to homicides this year, there's one high profile case from 2016 they are yet to charge someone over.
Last weekend marked two years since Upper Hutt woman Lois Tolley was shot at point blank range in her home.
Detective Senior Sergeant Glenn Barnett said they were closing in on the four people seen running from her home that night.
"In the next few months we're positive that there will be arrests in this case."
Who are the victims?
- Francis Tyson, 71, November 30, Lower Hutt. Murder charge laid.
- Baby girl, 3 months old, November 13, Porirua. No charges laid.
- Sosiua Helotu Ula,19, October 7, Porirua. Murder charge laid.
- Faapaia Fonoilaepa, 29, September 14, Lower Hutt. Murder charge laid.
- Glen Collins, 45, September 20, Upper Hutt. Murder charge laid
- Lincoln Wakefield, 5 months old, June 12, Upper Hutt. Murder charge laid.
- Paul Te Hiko, 40, March 7, Lower Hutt. Murder charge laid.
- Zena Campbell, 21, February 11, Wellington City. Murder charge laid.
