A juvenile court is required to hold a formal fitness hearing before transferring a pending wardship petition to superior court, even when the prosecution has directly filed a criminal complaint against the minor in an unrelated case. The prosecution filed two wardship petitions in juvenile court against the 16-year-old minor, alleging attempted murder and violation of a gang injunction. It simultaneously moved the court to find the minor unfit for juvenile court treatment in the attempted murder case. (Welf. & Inst. Code, § 707, subds. (b), (c).) After the prosecution filed an unrelated murder complaint against the minor in superior court, the juvenile court transferred the pending petitions to adult court, deciding that the direct filing of the criminal complaint constituted a finding of unfitness for juvenile court treatment. (Welf. & Inst. Code, § 707.01, subd. (a)(3)(A).) The minor sought writ of mandate. Held: Granted and remanded for a fitness hearing. Once the wardship petition is filed, the matter must remain in juvenile court unless the court finds the minor unfit for juvenile court treatment. (Welf. & Inst. Code, § 606.) Section 707.01, subdivision (a)(3) allows the juvenile court to transfer all pending petitions against a minor who was at least 16 years old at the time the offense was committed, once the minor has been found unamenable to juvenile court treatment under section 707. But section 606 requires that the fitness determination be made by the juvenile court, and a prosecutor’s charging decision is not equivalent to a judicial fitness determination. Although some of the same criteria may be used by a juvenile court in a fitness hearing and by a prosecutor in deciding to direct file a criminal complaint against a minor, the prosecution’s determination is directed by the efficient administration of criminal justice, not an evaluation of whether the minor is amenable to juvenile court treatment.