Police believe an aversion to "narking" is preventing the families of two Hawke's Bay homicide victims from justice being served.
Eddie Peters, 45, was found in a Flaxmere driveway early in the morning of 16 November 2018. He had been violently beaten, and died of his injuries eight days later.
Ariki Rigby, 18, was found dead in a burned-out vehicle in Havelock North on 5 September 2022.
Their families have teamed up with police to issue a fresh appeal for information on who killed them.
"We know there are people in our community who know what happened to Eddie and Ariki, and who was responsible," Detective Senior Sergeant James Keene said on Thursday.
"We also know there are a few reasons why people might not be talking - one of which is a belief that 'narking' is not the 'done' thing."
'Please do the right thing'
Peters' whānau said he was a "much-loved father" who was greatly missed.
"No matter how hard it is for you, no matter who you're trying to protect, we're begging you to please do the right thing - get in touch with police and share what you know."
Rigby's family said their grief was "profound, and still very raw".
"She had her whole life ahead of her and she should be busy living that life right now. Instead, we are preparing for our first Christmas without her."
They said it was "made worse by the fact nobody has been held accountable for her death".
"Think how you would feel if she was your daughter, sister or moko. Tell police what you know."
Keene said while the deaths were not linked, in both cases police "know there are people who have information and are choosing not to share that with us", possibly due to gang affiliations.
"We have two grieving whānau who need and deserve to see justice for the deaths of their loved ones. Please put yourselves in their shoes and tell police what you know, so that the people responsible can be held accountable."
Hundreds turned out for Rigby's funeral in September. Members of the public left written tributes, flowers and balloons at the site where her body was found, the River Road Recreational Reserve.
Peters' brother told Stuff in 2019 he lived a rough life, but was a gentle man "who would never hurt a fly".