Key Points:

A South Auckland babysitter has admitted murdering a 10-month-old girl she was entrusted to care for by the baby's family.

With her head hung low and tears running down her cheeks, Tiana Mary-Ann Kapea yesterday pleaded guilty in the High Court at Auckland to killing Jyniah Te Awa.

Jyniah died in September last year after a weekend of abuse at Kapea's hands, which included being kicked, hit on the head, smothered, thrown across the room and shaken with such vigour her head rolled back and forth.

Kapea also admitted a representative charge of cruelty to a child that covers what police have described as "systematic and deliberate abuse" that Jyniah suffered on many of the occasions Kapea looked after her.

The guilty pleas - made just over a year after Kapea was first arrested - were greeted with relief by Jyniah's grieving family, many of whom sat in court wearing T-shirts with pictures of their beloved baby girl on them.

Jyniah's mother, Lisa Cassidy, said the pleas and sentencing, which is set down for this month, meant the family could start to move forward. They could also begin next year without the burden of a looming trial.

"It just relieves a lot, it's sort of like we are getting towards the end. A whole brand new year without having to attend court or worry about it ... [but] I won't be completely happy until sentencing is done," she told the Herald.

Miss Cassidy is glad the wider community will find out the truth about what Kapea did to her daughter.

"It's all going to be out, everybody is going to know what sort of person she is ... and what she did. Half of her family members don't even know - they are still all supporting her."

Detective Sergeant Colin Higson, second in charge of the investigation, said the guilty pleas were a good outcome. "I think it's good that she's accepted responsibility for what she's done and it saves the family the emotional trauma of having to recount things [in court]."

Kapea was a trusted family friend.

She has been remanded in custody until her sentencing.

Sept 07: Jyniah Te Awa, 10 months, dies from non-accidental brain injuries.

Dec 07: Her babysitter Tiana Kapeais charged with murder.

Nov 08: Kapea pleads guilty to murder and cruelty to a child. She is now in custody awaiting sentencing.