For the parents of Riley Fox, the 3-year-old girl who was abducted and brutally murdered in the small town of Wilmington, Ill., in the summer of 2004, hunting for her killer has been a painful, six-year nightmare.
"Just to hear those words, 'We caught your baby's killer,' it was pretty emotional," said father Kevin Fox in an exclusive interview to air on "20/20."
Riley was kidnapped from the living room of her own home in 2004 and sexually assaulted, bound, gagged with duct tape and drowned. Her body was found face down in a creek in the Forsythe Woods, a public park about two miles from the Fox residence.
As years passed, the Foxes almost lost hope of finding the real killer. When they learned last month that police had tracked down the man believed to be Riley's murderer, Kevin and Melissa Fox were filled with mixed emotions.
"I'm still in shock. I have no words to even explain how I feel. For almost six years you thought this was going to be like a celebration day and it feels quite the opposite," said Kevin Fox.
Scott Eby, a 38-year-old imprisoned sex offender, was charged on five counts of first-degree murder and one count of predatory sexual assault last month after DNA evidence allegedly linked him to Riley. He is expected to plead not guilty.
Putting Eby's face to the long-unsolved mystery brought the Foxes a sense of vindication, but they said it has also been terrorizing to know the grisly details of how their daughter was murdered.
"He stole something very important from the world," said mother Melissa Fox. "I needed to know what happened to her and what she went through, but now it's kind of like torture. Now, it's like I'm torturing myself with those details. It's not at all what I expected."
CLICK HERE to see photos of Riley Fox and to find out details on the murder case
The Foxes' attorney, Kathleen Zellner, said Eby confessed to killing Riley after first burglarizing another house on the same block -- an important clue that the Foxes said police at the time ignored.
According to Zellner, Eby cut through the back door of the Fox house, pushed the door in, and saw Riley sleeping on the couch in the living room.
Zellner said Eby formed the intent to kidnap Riley after he saw that her father was asleep. He proceeded to get his car, put her in his trunk and drove to a nearby park, where he assaulted her on the floor of a public restroom.
Compounding their loss is the conviction that there were so many missed opportunities to catch the alleged killer quickly.
"My daughter got raped in a bathroom at Forsythe Woods and they didn't even process that bathroom [for DNA evidence]," Kevin Fox said. "He threw her underwear in a garbage can, and they didn't even search the garbage cans for it. They didn't find it."