Endia Martin's killer has been in custody since the 2014 shooting. Martin was only 14 when she and a group of friends were attacked by another girl.
The four-year-old legal saga was supposed to come to a close Wednesday morning, but the sentencing has been pushed back until June 20.
Associate Judge Stuart Paul Katz said the sentencing was delayed because a prosecutor assigned to the case left the states attorney's office.
In January, the defendant pleaded guilty to first degree murder. ABC7 is not naming her because she was charged as a juvenile.
The plea came less than a week before her scheduled trial in the 2014 shooting death of Martin.
The defendant was also 14 years old at the time and prosecutors said the shooting was instigated by a heated interaction on social media over a boy.
The teen shooter's uncle was convicted of providing the gun used in the incident. In 2016, he was sentenced to 100 years in prison.