Clark, 45, of 333 Baughman Ave., had worked as a baby sitter for the Arnolds for about three years, David Arnold said, and was especially close to Sophia.
Assistant Danville Police Chief Tom Bustle said that David Arnold came to the police station about 4:15 p.m. Friday to report his daughter missing. Sophia and Clark had last been seen at 8:30 a.m. and Clark had not picked up Sophia's brother after school as she normally did. Clark did not leave a note or contact the Arnolds, Bustle said.
"With all that information, we considered this might be something beyond the normal at that point," Bustle said. "We had no clue where she might have taken the child. It was just a big unknown."
After contacting Clark's friends for possible leads, police officers with several area agencies began sweeps of local locations but came up empty.
Kentucky State Police were also involved looking for Clark in Paris and Versailles, where she was known to have friends.
Just before 6 p.m., Bustle said police contacted state media outlets with information and pictures about the missing duo so they could be broadcast on the evening news.
The Amber Alert, which is only issued by KSP in emergencies after police conclude that a child faces serious risk, would not be broadcast until later in the evening.
She had been known to go missing
What convinced authorities to issue the Amber Alert was learning from Clark's friends that she "had been known to go missing for two or three days at a time without telling anybody," Bustle said.
"That played a big part in it," he said. "We felt that was enough to make us feel this child could be in serious danger."
After the Amber Alert was issued, the FBI and National Center for Missing and Exploited Children became involved in the search. The center dispatched a retired police officer to assist in the case, who was due to arrive Saturday morning before being called off, Bustle said.
The first 24 hours after a disappearance is crucial, Bustle said. An Amber Alert, which contains descriptions of the missing child, possible suspect and vehicle, is regularly flashed across TV screens and updated on news broadcasts so citizens can help in the search.
In this case, the Amber Alert produced no significant leads, Bustle said.
"Usually you get calls from family or friends so you can start narrowing your search down and get more specific leads," he said. "We didn't get any of those calls this time. We started to have some huge concerns."
"A roller coaster of emotions"
Throughout the ordeal, David Arnold and his wife, Melissa, went through "a roller coaster of emotions," Bustle said.
"They were calm in giving us the information and pictures we needed, but there were times when they were breaking down, just like I would have done if it had been my daughter," Bustle said.
After Sophia's safe return, Arnold said that he and his wife were just grateful and wanted to thank all those in the community who helped comfort them and tried to find their daughter.
Bustle said that Clark was cooperative with police after she returned. The criminal complaint for custodial interference was issued so authorities could detain Clark, he said. The investigation is continuing and additional charges could be filed, he said.
Staff Writer Terri Carter contributed to this report.