Indiana State Police Sgt. Curt Durnill said the body of a female infant matching the description of Shaylyn was found just after 6 p.m. in a remote area near the White River northeast of Gosport.
"Rural. Very rural. Right up against where the water would meet," Durnill said. "It appears that, where the river would flood, the body was found right in that area. It's a private access. It's on private property near Gosport."
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Kyle Parker, 22, of Spencer, was taken into custody in connection with the case.
Shaylyn's father Justin Ammerman identified Parker as a friend who had been at his house the night before Shaylyn's disappearance.
Court records show Parker has had past run-ins with the law in Owen County on charges of drug possession and criminal trespassing. RTV6 couldn't find any felony charges on his record.
Despite Thursday night's discovery and arrest, police will be talking with at least 3-4 persons of interest in the investigation. Police had not arrested anyone else in the case, and said no more arrests were expected at this time.
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Durnill said the investigation into Shaylyn's death was just beginning.
"Let me be really frank here: We've just started," Durnill said. "Please don't feel that just because we've made a body, just because we've made an arrest, that this case is over."
In a press conference Thursday night, Durnill praised the community for coming together in the search for Shaylyn.
"I've been on the force for 23 years, and I can't remember a time when the community's come together more than this," Durnill said. "You'd just see determination in people's eyes. Nobody's going home. Nobody's going to stop. I received hundreds of emails today, 'I have boots and a bottle of water and I want to help.' That's how tightknit this community is. It gives me goosebumps just talking about it."
Friday morning, Owen County Sheriff Leonard Sam Hobbs said, "The one thing that I'm positive of is that the baby's safe with God now."
After the news of her death was announced, Shaylyn's mother, Jessica Mae Stewart, posted this image to her Facebook wall: