A 17-year-old allegedly gunned down her church-going mother and stepfather inside their Georgia home before her younger sister discovered the dead couple.
Sarah Grace Patrick turned herself in at the Carroll County jail on Tuesday after she was charged with the Feb. 20 murders of Kristen Brock, 41, and James Brock, 45, WSB-TV reported.
Their bodies were discovered in bed at their Tyus home by the couple's 5-year-old daughter, and investigators said the alleged 17-year-old killer was the one to call 911.
"From the very moment the 911 call was received, a relentless investigation began," Carroll County Sheriff's Office spokeswoman Ashley Hulsey said during a press conference Tuesday.
At the murder scene, investigators immediately noticed there were no signs of forced entry into the home -- although one door of the house was left slightly ajar -- and nothing had been taken.
"Our team has sifted through mountains of physical and digital evidence and collaborated with the FBI and GBI crime lab," Hulsey said.
Hulsey also said another key piece of evidence they used to charge the teen was her tearful speech at her mother's funeral, which investigators believe was a ploy to help cover her tracks.
Authorities said it took months to charge the teen because investigators wanted to ensure they got the right person, who they believe orchestrated the "horrific crime."
Patrick -- who will be tried as an adult -- has been charged with two counts of murder and two counts of aggravated assault.
Investigators are still working to discover a motive for the killings.
"We don't know what goes through the mind of a child who wants to harm their parents," Hulsey said.
"She's 17. She's kind of been out on her own. She's lived with different family members and moved all over the place."
Even though Patrick has been charged, Hulsey said investigators aren't ruling anything out in this case, and are pursuing the possibility that more arrests will be made.
"Any information, no matter how small it may seem, could be just that key that cracks this case wide open," she said.
Hulsey said the tragedy of the murder is the trauma the couple's 5-year-old daughter will face finding their bodies.
"A little girl who was in the home, to me, she is probably the saddest victim in all of this," she said.
The couple were active members of the Catalyst Church, with parishioners telling Fox 5 Atlanta that they are remembered for their kind-hearted and generous loving nature.
"Kristen was bubbly and fun and she loved hugs. She never met a stranger. And James, he was a comical kind of guy. He would always crack jokes and always say something to make you laugh," Tasha Meza said.
"[Kristin] always encouraged you. She was definitely the friend that you would want to have around," another member of the church, Janelle Thompson, told the outlet.
Before the 17-year-old's arrest, members pleaded for the killer to turn themselves in.
"I just wish they would turn themselves in," Jonan Daniel said in February. "We all make mistakes, but this family doesn't need to suffer more."
The couple is survived by their seven children, whom they had together in their combined family.
If Patrick is convicted, she faces life in prison without the possibility of parole.