A California woman has pleaded guilty to torturing and murdering her young niece and nephew after their bodies were found dumped in a rented storage unit.

Tami Joy Huntsman, 41, took a plea deal which will see her sentenced to life in prison without the possibility of parole instead of the death penalty.

'She will die in prison,' prosecutor Berkley Brannon said, according to SFGate. The plea will also spare the victims' older sister from having to testify.

Huntsman was arrested after police discovered a 'severely abused' nine-year-old girl, who was starving and had multiple broken bones, in the back of an SUV parked in Quincy, California.

Cops then discovered the bodies of six-year-old Shaun Tara and three-year-old Delylah Tara, in a Redding storage unit in 2015.

Autopsies found that Shaun and Delylah were killed around Thanksgiving 2015, after the starving nine-year-old was caught stealing a bagel. The autopsy found they died as a result of sustained physical abuse.

Tami Joy Huntsman, 41, took a plea deal which will see her sentenced to life in prison without the possibility of parole instead of the death penalty

Huntsman admitted torturing and murdering her young niece and nephew after their bodies were found dumped in a rented storage unit

Huntsman, and her teenage boyfriend Gonzalo Curiel, then 17, were left to care for the three children after the children's mother was killed in a car crash, and their father - Huntsman's brother - was in jail in connection with a forest fire.

Two older children - 12-year-old male and female twins - who were at the East Quincy residence where Huntsman and Curiel were staying with a friend, were immediately placed in foster care, the Plumas News reported.

Salinas police chief Kelly McMillin described it as 'the most egregious child abuse homicide case I've ever seen'.

The bodies of three-year-old Delylah Tara (right) and six-year-old Shaun Tara (left) were dumped in a storage unit

The children were believed to have been staying with Huntsman after their mother died in a car accident and their father was arrested in connection with a 120-acre forest fire in El Dorado County, California

On Wednesday, Huntsman told the court that she and Curiel starved and beat the six-year-old boy and three-year-old girl before killing them.

Curiel, who was 17 at the time, has pleaded not guilty to murder and torture charges, and will go to trial on April 2. As he was a minor at the time, he is not eligible for the death penalty.

Cops were initially alerted after the found the siblings' older sister who showed clear signs of abuse.

Gruesome: Huntsman, who is believed to be their aunt, and her 17-year-old boyfriend, Gonzalo Curiel, faced charges of felony child abuse, torture, and mayhem after the gruesome discovery in Redding, California

Plumas County Sheriff Greg Hagwood said she weighed about 40 pounds, had broken bones in her shoulder, broken fingers, a dislocated jaw, and teeth that were missing or loose. She reportedly had open sores and was infested with lice.

Hagwood told the Plumas News: 'This has shaken my staff to the core.

'That little girl had been subjected to the most unspeakable measure of torture for an extended period of time. This is child abuse, the likes of which we haven't experienced here.'

Huntsman and Curiel were arrested and questioned about the girl and her younger brother Shaun, 6, and sister, Delylah, 3, who were then listed as missing.

Curiel reportedly told detectives they could find the missing children inside a pair of plastic bins in a storage container in Redding, about 150 miles from Quincy.

Social services had previously made four visits to Huntsman's home but found no evidence the children were at risk.

A commercial storage unit facility is shown last month, where two children were found dead in Redding

Police attended the storage locker in Redding after they arrested the pair in Quincy, California

T here were four complaints between September 2014 and August about general neglect, a category that includes poor supervision, improper feeding, lice infestation and dirty household conditions, Elliot Robinson, head of Monterey County Department of Social Services, told the San Francisco Chronicle, adding that none of the complaints alleged physical abuse.

He said: 'General neglect calls rarely will result in the removal of the child. More often than not it's about poverty.'

Social services officials were reviewing the agency's handling of the four neglect complaints.

Robinson told the San Francisco Chronicle: 'We're looking at the case to see if there's anything we should have done differently that could have prevented this tragedy.'

It is believed that the two children were killed in Salinas, California and dumped in Redding. Police began searching for the children after they found a badly injured nine-year-old girl in Quincy, California

Chief McMillin said Salinas police responded twice to Huntsman's house over a six month period to check on child abuse reports.

Officers didn't find anyone at home the first time and didn't see any evidence of neglect or abuse when they returned later.

Huntsman's Facebook profile claimed her job was: 'Being The Best Mom I Can Be'.

Huntsman's estranged husband spoke out last month and said she was never an 'evil' person.