A brutal kitchen brawl between a Conyers mother and her teenage twin daughters ended with the mother’s death, prosecutors said.

Nearly four years after Jarmecca "Nikki" Whitehead's spinal cord was fatally severed at the climax of the fight, one of her twins has admitted her part in the killing.

Tasmiyah Whitehead, 20, pleaded guilty Thursday to voluntary manslaughter, falsification in government matters and possession of a knife during the commission of a crime in the death of her mother.

She was sentenced to 30 years in prison.

Her identical twin sister, Jasmiyah Whitehead, goes to trial in March in connection with the killing and could face life in prison.

“I have read about … tragedies of epic proportion,” Rockdale County Superior Court Judge David Irwin said Thursday at Tasmiyah Whitehead’s plea hearing. “I had no idea what that was until today.”

Tasmiyah Whitehead and Jasmiyah Whitehead were 16 when they were arrested and charged with malice murder, felony murder and aggravated assault in connection with their mother’s death.

An apparent history of violent family turmoil had been brewing over some years and exploded on the morning of Jan. 13, 2010, prosecutors said.

The twins had been living with their great-grandmother Della Frazier and had been moved back to Conyers with Jarmecca Whitehead just a week earlier.

Rockdale District Attorney Richard R. Read said on Thursday that Tasmiyah recently told prosecutors she and her sister awoke that day late for school and encountered their mother in the kitchen.

“(Nikki) hit Jas with a pot,” Read said. “Tas took the pot from their mother and Nikki grabbed a steak knife.”

The fight began.

“There was name-calling and cursing and gouging and scratching and everybody was mad,” Read said. “During the fight, her mom was cut and stabbed.”

Tasmiyah Whitehead looked on stoically in handcuffs, leg irons and an orange Rockdale County Jail jumpsuit as Read described her accounts of the fight that led to her mother’s death.

At some point that January morning, the melee halted, and Jarmecca Whitehead left the house seeking help from a next-door neighbor, according to prosecutors.

When no one immediately answered the door, she returned home, Read said.

“Tas said Nikki came and sat down in the kitchen … she was tired,” Read said. “Tas said Nikki lunged at the knife. Eventually the blows necessary to bring about the death of Nikki Whitehead were given.”

Among her injuries, Jarmecca Whitehead suffered significant stab wounds to her lungs, jugular and the back of her neck, where her spinal cord was severed, prosecutors said.

Jasmiyah and Tasmiyah Whitehead went to school and flagged down a Rockdale County sheriff’s deputy driving by their home later that day, telling the deputy they found their mother dead, prosecutors said.

Conyers police investigating the death followed evidence, including cuts and bite marks on the twins after the fight, to implicate them in the death, authorities said.

They were arrested and charged after four months of police investigation, and both pleaded not guilty.

Prosecutors said strife between Frazier and Jarmecca Whitehead contributed to the conflict with the twins, authorities said.

Frazier was not available for comment Thursday.

Jarmecca Whitehead had been living with her daughters at Frazier’s home in Clarkston and moved them with her into her boyfriend’s home in Conyers, authorities said.

That’s when the girls’ grades began to drop and they started getting into trouble, Read said.

“This is a family that thrives in chaos,” Read said, reading notes from a juvenile court counselor who attempted to reconcile the tumult between Jarmecca Whitehead and her girls, who had sided with their great-grandmother Della Frazier. “All members – mom, great-grandmother and the girls – struggle to take their own responsibility for family stress. The adults in this family have failed to guide these children properly.”

From the time they became teens, the twins who had been straight-A students and Girl Scouts began rebelling against their mother, Read said.

Read said they despised Jarmecca Whitehead’s strict rules about boys and accusations of drug use while at the same time they alleged she was smoking marijuana and parading between boyfriends.

“Nikki believed they were sexually active, using marijuana and skipping school,” he said. “They believed she was a hypocrite because she was promiscuous and used marijuana.”

A 2008 fight with the girls ended in Jarmecca Whitehead being scratched by the then-teens and dragged across the floor, and prompted a juvenile court judge to send the twins back to Frazier’s home.

Their mother was killed just over a week after they were returned to her custody. Read said one of the twins even threatened fatal action during a counseling session before they moved back to Conyers.

“Jasmiyah said, ‘If I have to move back with her, I’ll kill her,’” he said in court Thursday.

A tearful Lynda Whitehead, Frazier’s daughter and Jarmecca Whitehead’s mother, told the court that her heart was broken. While she said she forgives the twins and loves them, she lamented that they weren’t held accountable.

“Unfortunately, my grandchildren never learned right from wrong … and that’s why we are here,” she said. “They should be in college, not sitting somewhere in jail.”

Jasmiyah and Tasmiyah Whitehead have been in jail since their arrest in May 2010.

Tasmiyah was moved to the Rockdale County jail when she turned 17 and will remain there until she is transferred to a state Department of Corrections facility to serve out the remainder of her sentence.

Jasmiyah is being held without bond in the Newton County jail in Covington and awaits her trial in March, prosecutors said.