Link to DOJ report for 2014 here.

Highlights:

• FBI’s CY 2014 statistics are similar to 2013. The majority of Indian country criminal investigations opened by the FBI were referred for prosecution.
• The majority of Indian country criminal cases opened by the USAOs were
  prosecuted.
• The most common reason FBI Indian country investigations were closed administratively without referral for prosecution was that the investigation concluded that no federal crime had occurred. Analysis of CY 2014 data indicates that 657 FBI Indian country investigations were closed administratively without referral to a prosecuting authority — approximately 32% of the investigations that were opened. Reasons for non-referral include deaths determined to be the result of natural causes, accident, or suicide (i.e., non-homicides; 20% in CY 2014 of all investigations not referred), and insufficient evidence of criminal activity (21% in CY 2014).
• All but 37 of the 148 death investigations that the FBI closed administratively in CY 2014 were closed because the FBI established that the death was due to causes other than homicide; i.e., accidents, suicide, or death due to natural causes.
• In 2014, the USAOs resolved more cases than in 2013. In 2014, the USAOs resolved 535 more cases than in 2013. A total of 3,930 Indian country matters were resolved in CY 2014, as compared to 3,395 cases in 2013.
• The USAO declination rate remained steady. USAO data for CY 2014 show that 34% (989) of all Indian country submissions for prosecution (2,941) were declined. In CY 2013, USAOs declined approximately 34% (853) of all (2,542) Indian country submissions for prosecution. USAO data for CY 2012 indicate that just under 31% (954) of all Indian country submissions for prosecution (2,542) were declined.
• The most common reason for declination by USAOs was insufficient evidence (59.6% in CY 2014, 56% in CY 2013, and 52% in CY 2012). The next most common reason for declination by USAOs was referral to another prosecuting authority (16.3% in CY 2014, 21% in CY 2013, and 24% in CY 2012).