Page three is especially telling:

The results of the statutes and Supreme Court opinions is a confusing maze of jurisdictional responsibility that paralyzes effective law enforcement on reservations. The FBI, the BIA, the state police, the local county sheriff's office, and the tribal police all have limited jurisdiction over crimes committed on Indian reservations, and it is not unusual to have all five agencies involved in at least the initial investigation of a single crime. But each agency's jurisdiction is so limited that violent criminals often fall through the cracks and avoid arrest, particularly if they happen to be white.

For instance, if a person is assaulted on a reservation, that crime is usually handled by the tribal police. But if the person assaulted is not a member of the tribe, the tribal police have no jurisdiction and the local police must be called in--if they are willing to investigate in the first place. Or if it is determined that the victim was sexually assaulted, the tribal police must hand the case over to the BIA police. And if the victim later dies, it becomes a murder case, which can be handled only by the FBI.