An Oak Grove couple has been convicted in federal court of an $800,000 tax fraud scheme, as well as mail fraud, money laundering, and using fictorious financial instruments.  According to the United States Attorney’s Office,  Joshua Simonson, 34, and his wife  Kristen Simonson, 35, were found guilty on a total of 11 counts.  The Simonsons reportedly ran a conspiracy to defraud the federal government by filing fraudulent tax returns. Sentencing hearings have not yet been scheduled for the couple.