Keenan said Brunn, who has no known criminal record, had keys to both the empty apartment and the trash compactor bin where Rivera's body was placed.

"We are confident that Brunn is the killer and that is why he is in custody," Keenan said, declining to detail what evidence investigators have against him.

According to an arrest warrant obtained by The Associated Press, Brunn was arrested on suspicion of murder and making false statements to authorities. The arrest warrant says, "the accused did unlawfully and with malice aforethought cause the death of Jorelys Rivera by hitting her on the head with a blunt object." No other details are contained in the document, which was filed Wednesday.

It was not immediately clear whether Brunn had an attorney. He was being held at the Cherokee County jail. Lt. Jay Baker with the Cherokee County Sheriff's Office said Brunn's initial appearance in Superior Court was set for Thursday.

Brunn, wearing a blue hooded sweat shirt and jeans, was arrested at the apartment complex and taken in handcuffs to a sheriff's patrol car surrounded by a handful of armed law enforcement officers. Video aired by WSB-TV shows Brunn keeping his head down and ignoring comments shouted by an observer.

Keenan said investigators focused on Brunn after receiving information from the public. Brunn had been under police surveillance since Tuesday night. Keenan said the investigation will continue for several months.

"This is a mammoth case," Keenan told reporters at a news conference in Canton. "We believe that this horrendous crime was planned and calculated, and we've recovered a lot of evidence."

Blue Ridge District Attorney Garry Moss said he had not yet decided whether to seek the death penalty.

On Wednesday, Canton Police Chief Jeff Lance thanked investigators and volunteers who searched for the slain child. About 65 local, state and federal investigators worked the case and several hundred interviews were conducted, authorities said.

"Our goal was to make an arrest for what has happened to this sweet, innocent little girl," Lance said.

When Rivera's body was found three days after she disappeared, the community where neighbors said they all knew each other was shaken and a makeshift memorial took root at the playground.

"I'm very concerned," Drew Baucom, 17, said soon after the killing. "It makes me feel like my home life is violated, that I can't trust somebody walking around that you think you may know, but you really don't. It just worries me that something else will happen like this."

Investigators said they received numerous tips from the public and that valuable evidence had come from apartment complex residents. They also interviewed several sex offenders living at the complex, Keenan said. On Tuesday he said officials had no reason to believe those sex offenders were involved.

Brunn began working for the apartment complex last month, according to residents and his Facebook page. He had previously lived in Dahlonega, Ga., and Dumfries, Va.

His mother, Karen-Ann Whiteley, filed for bankruptcy last month. She lives in Dahlonega, about 50 miles northeast of Canton where the killing happened.

In July, when Florida resident Casey Anthony was acquitted on charges she killed her daughter, Brunn wrote on Facebook that Anthony will "get hers." Ryan Brunn's Facebook page has since been disabled.

Nancy Hudgins, 57, who lives near trash bin where Rivera's body was found, said she talked with Brunn on Monday as police searched apartments in the complex for clues. She said Brunn told her that he was nervous about allowing officers into his apartment because he had beer bottles and is not of legal drinking age.

"He was just kind of scared about them going in," she said.

She said neighbors are feeling relieved that a suspect has been arrested.

"We're still kind of hurt real bad about this girl," Hudgins said. "We're really glad they did get the guy."

Another neighbor, Bernadette Merrill, 58, said she was particularly distressed that the child had been found in a trash bin.

"When it first happened, I didn't get any sleep," she said. "I just don't see a child being thrown away like that."

She said children often play unaccompanied in the apartment complex, and when the school bus pulls up outside the gate of the complex, most children would get off the bus and walk home unaccompanied. The killing changed that dynamic, Merrill said.

"Monday, every child had a hand," she said.

River Ridge Management Co., which runs the apartment complex, said all employees undergo and must pass background checks before being hired. Company officials declined to say whether Brunn had passed his background check.

The apartment complex's management is providing counseling and other support to residents, company officials said.