The teenager has been charged with second-degree felony murder as a juvenile. He is not accused of taking part in the stabbing, but in the robbery that preceded it, the authorities said.

During the questioning, he identified his two 14-year-old accomplices, who were initially questioned and released after they refused to answer questions on the advice of their lawyers.

Two months later, the Manhattan district attorney charged the other two boys, Rashaun Weaver and Luchiano Lewis, with second-degree murder and robbery. Mr. Weaver is accused of stabbing Ms. Majors and Mr. Lewis of holding her when she tried to flee, the authorities said. They are being tried as adults.

Ms. Majors’s murder rattled the city and evoked comparisons to the 1989 April attack on a jogger in Central Park. In that case, the police and prosecutors relied on tough interrogation techniques to obtain confessions from five teenagers, who were convicted in the brutal assault and rape of the jogger. The confessions were later proven to be false and the convictions were overturned.

The authorities say they took extra steps in Ms. Majors’s case to ensure that the teenagers were questioned in the presence of a lawyer or a legal guardian. The 13-year-old boy’s uncle was present when he was questioned.

But on Wednesday, Ms. Kaplan, a public defender, argued that the uncle, Roosevelt Davis, was no substitute for an attorney. Ms. Kaplan said that Mr. Davis did not possess the training to know Detective Acevedo could lie during the interview. Neither was Mr. Davis aware he could have stopped the questioning at any time.

Detective Acevedo told the judge that Mr. Davis told him, “I don’t have any issues talking with you guys” about his nephew’s arrest.