Her body was found in the woods nearby moments before a neighbor was found bloody and dead on the patio of his home.
Investigators said previously that they found a clue to Faye Marie Swetlik's disappearance on Thursday in the trash can of 30-year-old Coty Scott Taylor. By then, three days had passed since the girl disappeared.
In a news conference Tuesday, Byron Snellgrove, Cayce's director of public safety, revealed that the key pieces of evidence found in the trash can were a child's polka-dot boot and a soup ladle that had "freshly dug dirt in it."
He said "evidence leads us to believe that Taylor abducted and killed Faye," noting that DNA collected from both scenes connected the killer and victim.
Taylor was the "sole perpetrator" of the crime, Snellgrove said.
He added that Faye's body was moved during the cover of night to behind the townhouses where she was found.
Lexington County Coroner Margaret Fisher wept as she expressed her condolences for Faye's family. She then announced that Faye's death was a homicide and it took place within a few hours of the little girl being abducted.
Fisher also said an autopsy performed on Taylor showed his death was the result of "an incised wound to the neck." The manner was determined to have been suicide.
Taylor had been contacted and interviewed by law enforcement on Wednesday afternoon, Snellgrove said.
"He was cooperative and gave consent" to look through his home," Snellgrove said. "Those agents did not see anything that alerted them to believe that he had knowledge or was in any way involved in Faye's disappearance."
Faye was last seen getting off of a school bus in Cayce, a suburb of the state's capital Columbia.
In a Friday news conference, Sgt. Evan Antley said investigators followed Department of Sanitation trucks through the neighborhood Thursday morning and searched trash cans looking for any clues in Swetlik's disappearance. While searching in Taylor's trash can, Antley said they found a "critical piece of evidence" in Swetlik's case related to her missing person's flier.
Surveillance cameras captured what are believed to be the last images of the first grader. They show her getting off her school bus while wearing a black t-shirt with the word "peace" written on it.
WATCH: Video of missing South Carolina girl on school bus day she disappeared
Faye's mysterious disappearance garnered national intrigue. The FBI joined many other organizations going door-to-door and scouring any source for possible leads in the case.
Fliers with Faye's picture had appeared all over Cayce and people in the area tracked every development in the case.
"When she walks into a room she brightens it up. Everyone loves Faye," Snellgrove said Tuesday. "Faye loves dresses, fancy shoes, spending time with her family, cats and playing outside."
A public memorial for Faye will be held Friday evening at Trinity Baptist Church in Cayce.
SEE ALSO | 'I want my baby back:' Family prays for return of missing 6-year-old South Carolina girl Faye Swetlik
RELATED | I-Team: Strict standards in place to issue Amber Alerts