A California prison inmate locked up on a gang-related murder conviction led a scheme that defrauded the U.S. government out of more than $550 million in Covid-era federal tax credits, prosecutors said. The inmate, Kristopher Thomas, was also charged with running a drug trafficking operation from his cell at Kern Valley State Prison that shipped large amounts of methamphetamine to several states and smuggled fentanyl into that prison, court filings show. Thomas' mother, 55-year-old Kettisha Thompson-Dozier, and her spouse, Charmane Dozier, 44, who both live in Waldorf, Maryland, were charged with him in the tax credit scheme, along with Sharon Vance, 36, of Hawthorne, California, according to prosecutors. All four defendants are charged in that case with conspiracy to defraud the government with respect to claims. Five other people were charged