"This wasn't a 'whodunit,'" said Richland County Sheriff Leon Lott at a press conference confirming the body was 16-year-old Gabbiee's. "Almost immediately we were able to determine Freddie Grant was the man responsible for kidnapping Gabbiee. The challenge was we couldn't find Gabbiee."
Investigators flew to collect Grant from a Kentucky federal penitentiary Thursday morning and brought him back to Elgin, where he led them to her burial site.
"He's taken us there," said Lott. "He's told us. He's showed us."
Gabbiee vanished from her home August 18, 2012, and when her mother returned home that morning, she found Gabbiee's beeping alarm clock, but no sign of her daughter.
Grant, always the lone suspect, was arrested soon after on ammunition charges when investigators found shotgun shells and .38-caliber bullets, which he was prohibited from having thanks to a previous conviction.
Two days later, he was charged with kidnapping. Now, he will be charged with murder.
Lott said they had been in negotiations with Grant's lawyers, but only when Grant's daughter, Dominique, was arrested, did they get him to agree to a deal.
"That was, I guess, the breaking point as far as to getting Freddie to lead us to where Gabbiee was at," Lott said. "So I don't want anybody to think he did this out of his conscience or he felt bad for Gabbiee or [Gabbiee's mother] Elvia or this community. He didn't do that."
"He did it solely because his daughter was arrested and she was facing some very serious jail time," Lott said. "That's what we needed."
Dominique Grant, 27, was charged with accessory after the fact in July after she tried to dispose of Gabbiee's cell phone at a grocery store in Myrtle Beach.
Police, who have not speculated on a motive, believe Grant forced Gabbiee out of her mother's home in Columbia and took her to his home in Elgin. He had a key to the Swainson house because he was once Elvia Swainson's boyfriend.
Lott said they had searched the area where Gabbiee's body had been buried, but she was concealed too well. The body was taken to the Richland County Coroner's Office, where it was positively identified.
"The cadaver dog would not have been able to find it at the depth that it was," Lott said. "We just couldn't find it. There's just no way of finding it without someone taking us to that area and showing us."
"It kills us because we failed to find her," said Lott. "Even though we could not have saved her life, when she was buried. It hurts all of us to know that many, many people walked that area."
"This has been 357 days of terror that Gabbiee's mother and family had endured, that this community had endured," said Lott. "It's not the way we'd have liked this to have ended. We'd have liked to have found Gabbiee and brought her home to her momma."
Lott said the County is ready to "go to court today" to charge Grant with murder. He was sentenced in April to 212 months behind bars on the ammunition charges, and has not faced trial for the kidnapping charges.
Gabbiee was an honors student at Ridge View High School when she disappeared. She was just days away from starting her sophomore year.
Notable deaths of 2014 [PHOTOS]
Soviets call Reagan joke 'dangerous' [ARCHIVE]