This is the reporting
www.odt.co.nz/star-news/star-national/pair-jailed-torture-murder-teen
The judge 'said Winter, also known as Ashleigh Tonga, was the "dominant" offender and generally "in-charge". He believed the second strike offender became involved in the murder "because [she] found the situation exciting".'
No mention of the details of the 'first strike'.
For that you'll need to refer to the official court proceedings
www.courtsofnz.govt.nz/assets/cases/R-v-Winter-Te-Amo.pdf
(very graphic)
Your first strike offending occurred in 2014 when you attempted to rape a woman in circumstances where you first assaulted her with weapons and also tried to force her to give you oral sex.
Note that, somehow, despite Winter being indubitably the instigator, and having a far worse criminal history, with the co-defendant merely 'joining in', Winter gets a 10% discount on his sentence.
The judge notes of the co-defendant:
You became involved in petty crime which became more serious by 2017. On 16 January 2018 you were sentenced to one year and two months’ imprisonment for offences of violence and dishonesty.
A combination of drug and alcohol intoxication, an established pattern of low self-control, a history of emotion suppression and vulnerability to the influence of others, and a dominant co-offender who had a strong grievance against the 17 year old female victim, may explain why Mr Te Amo exhibited the capacity to engage in extreme violence
The Crown submits I should uplift your minimum period of imprisonment to take account of this offending. Your counsel suggests a lesser uplift. I think your previous offending means there should be an uplift in the interests of community safety. I will adopt your lawyer’s suggestion of six months. (!)
Taking your personal circumstances together, I find myself largely in
agreement with Mr Goodwin. I have decided I will reduce the starting point by 10 per cent.
So Winter gets 19 years + 4 months for murder, + 7 years for kidnapping, and Te Amo gets 19 years for murder + 7 years for kidnapping.