Prosecutors on Friday rejected Hunter Biden’s claims that his criminal case should be dismissed because it had been “infected” by the arrest of a key witness in a separate investigation into him by House Republicans. Biden had claimed that Alexander Smirnov’s claims that Biden and his father had taken bribes from individuals in Ukraine had caused a knock-on effect on the separate federal charges involving tax evasion and gun violations. Smirnov had been a key witness in the GOP’s investigation into business dealings involving Biden and his father, then Vice President Joe Biden. He has since be…