A Dahlonega man who pleaded guilty earlier this week of molesting and murdering a 7-year-old girl in a Canton apartment complex has committed suicide, officials said.

Ryan Brunn was found unresponsive in his cell at a state prison in Jackson around 4:15 p.m. Thursday afternoon, Kristen Stancil, a spokeswoman for the state's Department of Corrections, said.

By 5:37 p.m., Brunn was pronounced dead at a local hospital, Stancil said.

Brunn, the 20-year-old maintenance man who pleaded guilty Tuesday to the death of Jorelys Rivera, had been in the Georgia Diagnostic and Classification prison since then.

Stancil said the Georgia Bureau of Investigation is looking into the incident, but that it appears Brunn died from suicide.

Brunn was sentenced Tuesday to serve life in prison without parole for the Dec. 2 killing of the 7-year-old Rivera. He described in detail Tuesday how he carried out the crime at the Canton apartment complex where he had lived and worked as a maintenance man for about a month.

Before moving to Canton, Brunn lived in Dahlonega.

Rivera was reported missing after she left the complex's playground to retrieve sodas at her apartment for her friends.

Brunn described in detail to the court how he lured the girl into a vacant apartment and sexually assaulted her.

After Brunn sexually assaulted Rivera, he said he was afraid she would tell her parents so he "cut her."

When the girl didn't die right away, he beat and stabbed her.

Then he put her body in a blanket and dumped it in a trash compactor at the complex where it was found.

In court, Brunn apologized to the girl's family members who sobbed in the front row of the courtroom when he graphically described how he killed her.

The news of Brunn's death came the same day that Canton officials announced its Police Chief Jeff Lance had resigned after a scathing report found he took a "laid back" approach to the search for Rivera.

Brunn's defense attorney, David Cannon, did not immediately return calls seeking comment. Cherokee County District Attorney Garry Moss also did not immediately return calls.

Lance stepped down after the 17-page review revealed his department of about 50 officers violated several of its own policies and made many mistakes in the search for Rivera, said city manager Scott Wood.

A call to Lance for comment was not immediately returned.

The inquiry said there was little doubt that Rivera was already dead by the time Canton police received the missing child report. But it said if another such report were handled in the same manner, police "may indeed miss an opportunity to save a victim's life."

The review found the officer who responded to the initial call treated the case as a routine one that "would be solved in the same manner as dozens of other such cases that the agency had handled in 2011."

Local officers arriving to search for Rivera failed to activate their dash-board cameras to record the scene, failed to immediately determine if any sexual predators lived or worked nearby, and didn't report her case to a national registry until almost a day after she went missing, the report said.

The report said Lance didn't arrive at the apartment complex in the town of about 23,000 until around 10:15 a.m. the next morning — about 17 hours after the child was last seen. When he did arrive, it said he was talking to several other officers about the "Georgia game" and eventually turned the TV to a football game.

"Personnel present at the scene frequently characterized the chief's level of concern as ‘laid back,'" the report said.

Lance failed to launch a separate criminal investigation or heed advice to process Rivera's home as a crime scene, the report said.

Other problems with the investigation surfaced earlier. A Cherokee County deputy who failed to immediately report seeing drops of blood in an apartment during the search for the girl was earlier ordered to undergo additional training.

That was not included in the latest report.

Wood, the city manager, said the review should answer questions that were raised about the department's policies and procedures.

"Although sadly the family must still deal with the heartache and loss of this young child, from a legal perspective the matter has now been fully concluded," he said in a statement.

When Brunn was found unresponsive in his cell Thursday, he had been alone, Stancil said.

Another spokeswoman for the Department of Corrections, Gwendolyn Hogan, said Brunn was immediately transported to a hospital, where nearly an hour and a half later he was declared dead.

The GBI is treating the investigation as a death investigation and not yet a suicide, said spokesman John Bankhead.

Agents out of the bureau's Milledgeville office were investigating the scene at the prison Thursday night.

Bureau officials expected to perform an autopsy on Brunn's body by today if it arrived to the Decatur crime lab on time, Bankhead said.

Until then, the bureau would not comment on an apparent cause of death.

The bureau investigates all "in custody" deaths.

The Associated Press contributed to this report.