Faye Swetlik was found in the woods between her house and an auto parts store, investigators said in a news conference Friday. Taylor's body was found inside his home nearby.
Investigators said they believe these two deaths are linked, but would not elaborate on the evidence that connects them.
Investigators said Swetlik's death is being treated as a homicide. This comes four days after the young girl was last seen getting off of a school bus in Cayce, a suburb of the state's capital Columbia.
No arrests have been made, and investigators said they have not identified any persons of interest in her death.
"This is a fluid situation, and we're working diligently on it," said Byron Snelgrove, Cayce's director of public safety.
In Friday's 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.
He would not elaborate on what that evidence was, but said it was a "critical piece of evidence that would have been listed on her missing person's flier."
Antley said investigators began planning another methodical search of the area, but during the early planning stages of that search, Snelgrove found Swetlik's body.
"We believe that Faye had not been in that location for a very long time at all," Antley said during the news conference.
Lexington County Coroner Margaret Fisher said Taylor's autopsy will be released Saturday.
"He was a neighbor," Antley said. "He was not a relative. He was not a friend. He was merely a neighbor that lived in Churchill Heights."
Antley said Taylor had no criminal history.
Investigators said there is no danger to the public.
"We want more information about Coty Taylor starting at 3:44 Monday afternoon up until the time we found his body," Antley said.
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."
SEE ALSO | 'I want my baby back:' Family prays for return of missing 6-year-old South Carolina girl Faye Swetlik
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