Two former Detroit principals were hit with prison time Wednesday for a fraud scheme that defrauded the public school system out of $2.7 million. Ronnie Sims and Nina Graves-Hicks are just two out of 12 principals to be charged in the scheme, in which prosecutors say the officials took kickbacks from a vendor and submitted fake invoices for supplies. School employees were even given gift cards and cash, prosecutors said. Sims took more than $58,000, while Graves-Hicks got more than $27,000 in gift cards as part of the scheme, prosecutors said. Sims has been sentenced to one year and three months in prison, while Graves-Hicks got one year. Norman Shy, a vendor who prosecutors say paid $900,000 in kickbacks, was sentenced Tuesday to five years in prison.