JACKSONVILLE, Fla. -

The Jacksonville Sheriff's Office interrogation of then-12-year-old Cristian Fernandez, who pleaded guilty this month to manslaughter and aggravated battery in the death of his 2-year-old half brother, was released to Channel 4 on Monday.

The interview and confession recorded by detectives were ultimately thrown out by a judge after she ruled the boy hadn't fully understood his Miranda rights or what he was doing when he waived them.

Fernandez was arrested and interrogated in March 2011. He was charged with murder and became Duval County's youngest-ever murder suspect.

The interrogation video lasts about an hour and 24 minutes in its entirety, but Fernandez sits in the interview room for more than 20 minutes before a female detective comes in. They then go through his Miranda rights a short time later.

UNCUT:  JSO detective interviews Cristian Fernandez

"You don't have to talk to me," Detective Nechelle Soehlig tells Fernandez. "I want you to talk to me,but you don't have to talk to me, OK?"

Cristian Fernandez interrogation About six minutes later, the boy, using a doll, shows the detective how he broke David Galarriago's leg in an incident in January 2011.

"Did you hear a snap?" the detective asked.

"Well, sort of," Fernandez said. "He started crying, so I stopped."

The two then started talking about the toddler's fatal head injuries. Fernandez said Galarriago (pictured, below) was carrying books over his head when the books fell, then Galarriago fell. The detective told Fernandez repeatedly that couldn't be the truth.

There were long pauses in which they just looked at each other. She asked him to tell the truth, to do the right thing for Galarriogo's sake, and that he didn't have to be scared. She said, "You feel bad about what happened tonight?" And he answered yes.

David Galarriago Then Fernandez confesses.

"Did you hit him with something?" the detective asked.

"No," Fernandez said.

"What happened?" the detective asked.

"I pushed him against the book shelf," Fernandez said.

"How did you do that? Why'd you push him? Were you angry?" the detective asked.

"Yes, about something my stepdad did to me," Fernandez said.

"Why tonight?" the detective asked.

"Because I was thinking about it," Fernandez said.