SIOUX FALLS, S.D. (AP) — A backlog of mental competency evaluations of criminal suspects in South Dakota is taxing county budgets and raising concerns about the rights of defendants.

The Argus Leader reports there were 147 requests in state court for mental competency exams in fiscal 2015, and the state's mental hospital conducts only 36 annually.

Minnehaha County spent $100,000 last year on evaluations by private psychiatrists, who charge up to 10 times more than the state. County Commissioner Jeff Barth says "it's a heavy burden."

The backlog is due to a growing number of cases involving mental health issues. It's left some defendants in jail for half a year or more while they wait for an exam.

The American Civil Liberties Union encourages officials to develop a funding formula to address the issue.

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