Idaho Code § 31-2611

The county commissioners of each county in this state are hereby authorized and directed to set apart at their first meeting in October of each year, from any funds then in the county treasury, not specially appropriated or set aside for other purposes, in an amount to be fixed by said board of county commissioners, a sum of money not less than one hundred dollars ($100) and not more than one thousand dollars ($1000), to be used by the prosecuting attorney of each county as a contingent fund for the purpose of defraying such necessary expenses as are not otherwise specifically provided for in the trial and preparation for trial of criminal cases, and in the payment of such necessary expenses as are not otherwise provided for in conducting investigations by the grand jury.