A prosecution is not a bar within the meaning of section 109 of this title (relating to when prosecution barred by former prosecution for the same offense) through section 111 of this title (relating to when prosecution barred by former prosecution in another jurisdiction) under any of the following circumstances:
(1) The former prosecution was before a court which lacked jurisdiction over the defendant or the offense.
(2) The former prosecution was procured by the defendant without the knowledge of the appropriate prosecuting officer and with the purpose of avoiding the sentence which might otherwise be imposed.
(3) The former prosecution resulted in a judgment of conviction which was held invalid in a subsequent proceeding on a writ of habeas corpus, coram nobis or similar process.