Justin Robinson, 16, admitted to strangling Clayton Middle School student Autumn Pasquale after pleading guilty Wednesday to aggravated manslaughter, according to law enforcement sources.

Robinson, who was 15 when he was arrested with his then-17-year-old brother Donte for the October murder, was "voluntarily waived to adult court" in a hearing this morning. He immediately entered his guilty plea before Judge Walter Marshall Jr. and "admitted to choking to death Autumn Pasquale," according to sources.

The plea agreement carries a prison term of 17 years, of which 85 percent must be served before parole eligibility. Justin Robinson, of Clayton, is set to be sentenced in Sept. 12. According to law enforcement sources, today's hearing focused only on Justin.

The Robinson brothers were arrested and charged with Autumn's murder days after the 12-year-old Clayton girl went missing in October. Authorities said Autumn brought her bike to the boys' East Clayton Avenue home on Oct. 20, 2012 after Justin Robinson invited her there to work on her bike and exchange parts. Her parents reported her missing that night.

After a massive search through the South Jersey borough and surrounding towns, the girl's remains were found that Monday in a recycling bin on an abandoned property next door to the Robinsons' home.

(LEFT) Image of Donte Robinson, 17, taken from Twitter. (RIGHT) Image of Justin Robinson, 15, taken from Facebook. Both boys have been charged in the murder of Autumn Pasquale in Clayton, NJ.

The boys were arrested hours after Autumn’s body was found.

The Clayton girl's case had been in the hands of the Gloucester County Prosecutor's Offices since October, but a notice of potential litigation against the office required the case to be transferred to the neighboring county.

Family Division Superior Court Judge Colleen Maier, seated in Woodbury, ruled last year to close any court proceedings related to the juveniles charged with Autumn’s murder. All parties related to the juvenile case have been prohibited from discussing it.

Before the case was transferred, the Gloucester County Prosecutor’s Office did request the brothers be waived to adult court.

During a press conference held by the Camden County Prosecutor's Office this afternoon in Camden, Prosecutor Warren Faulk said Justin claimed sole responsibility.

"I lured a girl I knew was Autumn to the house with Facebook messages," Robinson said in court, according to West Deptford Patch. "I put my hands around her neck to choke her. I realized it could've caused her death, and I understand it did."

Faulk said he could not speak as to whether the admission impacts Donte's case because the office and other parties are still under a gag order by the judge, since Donte has not been waived to adult court.

Until Justin's admission of guilt today, Faulk said "proving without reasonable doubt (Justin) was the killer would have been difficult."

Faulk said the plea deal was struck because Justin admitted sole responsibility. Had he remained in juvenile court, Faulk said, he faced a maximum sentence of 20 years and only one-third of it — or seven years — would have had to been served before being eligible for parole.