Sheriff Darren White and Barnett's lawyer said the boy readily admitted to having sex with Daisy Coleman.
"They admitted that they had sex, but in their mind, they didn't necessarily think they did anything wrong," White told ABC News.
"In the state of Missouri, it is not illegal for a 17-year-old to have sex with a 14-year-old, but it is illegal for someone to have sex with someone who was incapacitated. And that's where the crime occurred," he said.
The prosecution of the sexual assault charge collapsed when the girls were asked about what occurred that night and they invoked the Fifth Amendment, Rice and Sundell said. Melinda Coleman insists the girls did not take the Fifth.
Barnett was then charged with endangering a child for allegedly dumping her outside her house. That charge was also subsequently, the sheriff said, because Daisy Coleman kept changing her story.
Melinda Coleman told ABC News she found her daughter outside the house about 5 a.m. in 22 degree lightly dressed and with her hair frozen. But Sundell said his client denies dumping the girl's outside.
Immediately after the boys were charged, the Coleman family said they began to receive backlash from the community.
Fearing for her children's safety, Coleman said she moved her family out of town and shortly after that her house burned down. The cause of the fire is under investigation.