There is no federal juvenile court, but the federal courts can and do handle juvenile cases, but hardly ever. They may likely defer to the state courts to take this case. I would think that no DA would prosecute a 12 year old for this, but some have in the past. What you need is a lawyer well versed in internet sex crimes and not just juvenile cases because of the sex offender implications of conviction.
It is very unlikely that your brother would be prosecuted in federal court because Pineville would have jurisdiction, the State has programs available, I do not see this as a crime of violence although it is defined as such under the habitual offender law and the federal sentencing guidelines, there is no substantial federal interest. If he is prosecuted it would be in juvenile court if Pineville(which I do not think it does) has a juvenile court or district court sitting as a juvenile court.
18 U.S.C. 5032 provides that the Attorney General, after investigation, must certify to the appropriate district court of the United States that (1) the juvenile court or other appropriate court of a State does not have jurisdiction or refuses to assume jurisdiction over said juvenile with respect to such alleged act of juvenile delinquency, (2) the State does not have available programs and services adequate for the needs of juveniles, or (3) the offense charged is a crime of violence that is a felony or an offense described in the statute, and that there is a substantial Federal interest in the case or the offense to warrant the exercise of Federal jurisdiction.
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