Law enforcement authorities raised concerns Tuesday that the drug testing scandal that erupted earlier this year at a laboratory run by the state Department of Public Health will continue to have fallout and that dangerous criminals will return to neighborhoods.

Boston Police Commissioner Edward F. Davis told a legislative committee Wednesday that he fears that a backlog of cases at the State Police crime lab, made worse by the scandal, will spur judges to release criminal defendants to the streets, instead of holding them, while their cases languish in the courts.