"We anticipate that this engagement will be finalized within 30 days and fees shall not exceed $50,000," writes Bistrow in the letter.
Both Derickson and Kaites are with the law firm Ridenour, Hienton & Lewis. Ridenour, et al., is on the list of firms approved by the AG's office to accept state government cases.
According to AG spokeswoman Stephanie Grisham, the firm has taken four such assignments since 2011, including this current internal investigation.
Additionally, records online with the Arizona Secretary of State's Office show that both Kaites and Derickson previously have contributed to Horne's campaign for AG.
Derickson made a $300 contribution to Horne, dated March 28, 2011. Kaites has made two contributions, one in 2011 for $840. And another in 2012 for $840.
Other members of the firm also have contributed to Horne, including William G. Ridenour, the firm's managing partner and founder. The total amount to Horne from members of the firm is more than $6,000.