The 15-year-old watched as the 7-year-old was raped by as many as seven men and boys in a vacant apartment near the girls' Trenton home on March 28, police said. As many as a dozen people were at the party in a crime-plagued public housing complex a mile from the dome of the New Jersey statehouse, investigators said.
The teenage girl originally was charged with aggravated sexual assault, criminal restraint, terroristic threats, promoting prostitution and endangering the welfare of a minor, and Mercer County prosecutor Joseph L. Bocchini Jr. had said he would push to try her as an adult. On Tuesday, the girl pleaded guilty in juvenile court to child endangerment and was sentenced to a year in juvenile detention, where she has been since her March 30 arrest.
The girl would have faced much more time if convicted of the other charges.
As part of her plea, Mercer County Superior Court Judge F. Lee Forrester ordered her to have no contact with her stepsister and provide truthful testimony and cooperation with prosecutors, who have related cases against five other people.
A telephone call to the teenage stepsister's public defender wasn't immediately returned Thursday.
Defense attorneys immediately questioned whether the younger girl was assaulted, and prosecutors admitted in court papers that preliminary DNA tests showed no semen was found in samples taken from her.
Besides the older stepsister, two men and three boys ages 13, 14 and 17 also have been charged in the case. The three boys are expected in juvenile court later this month.
The state offered plea deals to the juveniles in exchange for testimony against the men, assistant prosecutor Jennifer Downing has said.
Attorney Mark Fury, representing the youngest boy, said all the boys have been offered plea deals similar to the older stepsister's. He said he was unsure whether his client would accept the offer.
"Whatever happened, he wasn't there for it," Fury said.
The Rowan Towers building where the party occurred is in the downtown Trenton area and is surrounded by blocks of abandoned, boarded-up homes. Residents said security was long a problem there.