RICHMOND, Va. -- Richmond prosecutors decided to set aside, or in legal terms nolle prosse, charges against the teenager accused of beating eight-year-old Marty Cobb to death.

During a Friday morning motions hearing, prosecutors said they were still waiting for lab results on evidence recently submitted to the state crime lab.

Those test results could take up to two months to come back. City prosecutors said without knowing what the lab results would reveal, it would not be wise to proceed with the case against 16-year-old Mairese Washington.

Richmond Commonwealth's Attorney Mike Herring said Washington would not be a threat to the community and that his office planned to re-indict the teenager once the lab results return.

Washington was charged with first-degree murder in the May beating death of Marty Cobb. Family members said Cobb was defending his 12-year-old sister from Washington when the teen attacked Marty.

Washington was arrested two days later in connection with the homicide.

Prosecutors say that Washington will remain in juvenile detention, and cited "other matters."

In 2010, when Washington was 12 years old, a mother told CBS 6 that he attacked her then three-year-old son with a hammer. She said that Washington lived nearby and lured her son, then three-years-old, into another home and viciously beat him.

Heather Arrington was horrified to learn that the same person who attacked her son is now charged with murder. She said that after her son's attack prosecutors explained that her son’s attacker would get mandated mental health treatment, medication and counseling.

She said she was upset that she never received notification that the suspect was released from custody.