Murder charge in cold case death of baby twin Karlos Stephens in Rotorua in 2014

Murder charge against man for allegedly killing 10-month-old Karlos Stephens comes as new data shows 82 children younger than 5 were killed between 2007 and 2016.

A man has been charged with murder just weeks after police re-opened a cold investigation into the death of a baby twin.

Karlos Stephens was just 10 months old when he died in Rotorua Hospital in November 2014 and the senior detective leading the inquiry said the explanation for his injuries was "vague".

"We've never been totally happy with the version of events we've been given," Detective Senior Sergeant Lindsay Pilbrow told the Herald three weeks ago.

Detective Inspector Mark Loper confirmed a 59-year-old man had been charged with murder but said he could not comment further as the matter was before the courts.

The man appeared in Rotorua District Court this afternoon and he was remanded without plea until October 19.

Pilbrow would not be drawn on the exact nature of the injuries - or what possibly caused them - other than to say Karlos suffered a "significant" head injuries.

Karlos and his twin brother were living with extended family at the time of his death on November 30, 2014.

Those caregivers were not home in the days when the injuries were likely to have been inflicted and had been co-operative with police, said Pilbrow.

But the severe nature of Karlos' injuries did not match with the explanations given by the adults living in the house in the days leading up to his death, which Pilbrow described as vague.

"The explanation would be ... there's a lack of explanation," said Pilbrow.

"There's a lack of explanation from a small number of specific people who had care of these young children around the events of the weekend, the night before, and how this young baby could have received these injuries."

Pilbrow urged anyone with knowledge of what happened to tell the police.

"Baby Karlos isn't here now to speak for himself. There are people who know what happened and they need to step forward."

Horrific rates

The Bay of Plenty has one of the worst rates of child abuse in New Zealand and Pilbrow, who is the police district's manager for child protection, urged people to keep their eyes open.

Detective Senior Sergeant Lindsay Pilbrow is the head of child protection in the Bay of Plenty. Photo / BOP Times.

"I think it's important people be very vigilant as to what's going on in family and friends' homes. To not be scared to step forward and ask those tough questions."

New Zealand has one of the worst rates of child abuse in the developed world.

The actual numbers of child homicides can vary, depending on source, as investigations into suspicious deaths can take months or even years to finalise.

But new data released this week shows 82 children younger than 5 were victims of murder or manslaughter between 2007 and 2016 - or 12 per cent of all homicides in New Zealand over the time period.