OKLAHOMA CITY (AP) - A lack of internal controls, a greater law enforcement focus on corruption and human nature may all factor into a series of recent cases related to American Indian tribes, a federal prosecutor said Monday.

A federal jury last week convicted a former secretary-treasurer for the Apache Tribe on 33 embezzlement counts, accusing her of diverting tribal tax revenue into a bank account she controlled.

In another case, an ex-member of the Seminole Nation Council pleaded guilty last week to obstruction of the due administration of justice, stemming from allegations he accepted bribes from a tribal casino supplier in exchange for his power to impact business transactions.

John Richter, the U.S. Attorney for the Western District of Oklahoma, said Monday it’s not always fair to generalize, but what is being seen in some recent tribal-related cases occurs to some degree in any institution, be it political or financial.

“What we find in these investigations is individuals who have essentially used tribal funds as sort of their personal piggy banks,” said Richter, whose office handled the Apache Tribe case and a series of cases involving former officials with the Cheyenne and Arapaho Tribes.

“Instead of serving as duly elected officials or public officials and meeting their fiduciary responsibilities to use tribal funds to the benefit of tribal members, they’ve chosen to use tribal funds for their own personal benefit and aggrandizement.”

Doug Horn, the first assistant U.S. attorney for the Eastern District of Oklahoma, said there hasn’t been an increased effort at tribe-related prosecutions by that office.

“We’ve always had at least two attorneys out of our office who do nothing but Indian crimes” or crimes on Indian land, said Horn, whose office handled the Seminole Nation case.

Horn declined to answer questions about the Seminole Nation case, saying it was still under investigation. Assistant U.S. Attorney Linda Epperley, who handled the case, was not available for comment.

Calls from The Associated Press seeking comment about the cases from officials with the Cheyenne and Arapaho Tribes and the Seminole Nation weren’t immediately returned on Monday.

According to prosecutors, evidence showed that Emily Saupitty spent money embezzled from the Apache Tribe on items like travel and to pay people for political support as she ran for tribal offices.

Saupitty, 53, of Apache, said Monday the case involved a tribal dispute and she was “found guilty of helping my people.”

“They said I wasn’t a tax commissioner, but I never legally have been taken out” of that position, she said. “The other issue was whether I had the authority to continue to operate in the manner that they allowed me since 2002.”

Saupitty said a percentage of tribal tax collections was supposed to be used to pay for the tribe’s tax commission expenses, including an attorney who helped her conduct investigations.

She also said tribal Chairman Alonzo Chalepah was unqualified to speak or act on behalf of the tribe. Members voted to recall Chalepah and Vice Chairman Mary Rivera at a special meeting, but the vote has been called unconstitutional.

Richter said federal prosecutors are sometimes put in the position of discerning whether an allegation by a tribal member against an official is politically motivated or based on facts.

“Someone is using the allegation for political advantage and it’s often true, as was evidenced by Emily Saupitty’s case,” he said.

In the Seminole Nation case, Ricky Van Deer entered a guilty plea just as his trial was about to begin. Deer’s telephone number in Seminole is unpublished and he couldn’t be reached for comment.

Richter said with all embezzlement cases, control mechanisms have failed at some point.

“We see, depending on the tribe or the political institution, differing degrees of record keeping in terms of quality and quantity,” he said. “But certainly, the better your internal accounting controls, the harder it is for individuals who wish to embezzle.”

Richter said the number of tribe-related corruption cases in the past 18 months also is a testament to his office’s success in uncovering and prosecuting crimes.

“There has been a focus on public corruption during my tenure and this is one of the fruits of it,” he said.