Police arrested the 16-year-old twin daughters of Conyers murder victim Jarmecca "Nikki" Whitehead Friday morning and charged them with the murder of their mother.

Tasmiyah Whitehead and Jasmiyah Whitehead will be tried as adults, according to Conyers Police Department Chief Gene Wilson, due to the nature of the crime.

"This investigation has taken place over a several month period of time," said Wilson, and involved the Conyers Police, Rockdale County Sheriff's Office, and the Rockdale County District Attorney's Office.

"As the investigation went on, the evidence that was sent to the Georgia Bureau of Investigations to be processed pointed clearly to who was responsible for the murder." He declined to describe that evidence. He also said he did not know of any other weapon involved other than the knife.

"It was a brutal murder. She was stabbed and beaten to death," he said. "As for the motive, I just don't know."

"Any murder is a terrible crime. It's the ultimate crime. But when you have family on family, that makes it worse."

Whitehead, 34, was found stabbed to death on January 13 at 2020 Appaloosa Way in the gated Bridle Ridge subdivision, off of Dogwood Drive. The girls had reportedly come out of the house screaming and flagged down a deputy who happened to be in the neighborhood around 3 p.m. They told the deputy that they had found their mother's body when they returned home from school.

The girls were taken into custody by DFACS after the incident and had been living separately in Clarkston and Stone Mountain but had both been attending Tucker High School. One was arrested at the location where she was living in Clarkston and the other was arrested at school. Wilson said one of the girls was passive during the arrest while the other was hostile, but that neither showed surprise.

Rockdale County District Attorney Richard Read said the girls were being kept at separate youth detention facilities.

The girls had reportedly attended Rockdale County High School while they were living in the county.

Yucca Harris, a family friend of Whitehead since childhood, said the whole situation was hard on Whitehead's family and friends, including Whitehead's mother, who was at a loss for words.

"We don't know where to go from here," said Harris, who had heard about the arrest through word of mouth and had been in court while the girls were charged this afternoon.

"They showed no remorse. No emotion," said Harris. "They said nothing."

Harris said the girls had jumped on and attacked Whitehead in an incident about two years ago, but Whitehead was able to get away. After that incident, the girls reportedly went to live with their great grandmother. After two years, when the girls weren't doing any better, according to Harris, they were put back into Whitehead's custody. Harris said they had been with their mother for about two weeks before the murder.

Read said normally, a case will go before a grand jury in about 30 to 60 days, and then be up for arraignment 30 days after any indictment.