BISMARCK, N.D. (AP) — An attorney for a South Dakota man says DNA evidence found on a cigarette butt doesn’t prove his client participated in a riot during the Dakota Access pipeline protest three years ago.

The Bismarck Tribune reports attorney Bruce Nestor on Monday filed a motion in state court seeking dismissal of the charges against Lawrence Malcolm Jr., of Sisseton.

Nestor says it’s impossible to determine where the butt originated or how long it might have been there.

Prosecutors charged Malcolm earlier this month with felony conspiracy to commit criminal mischief and engaging in a riot.

The charges relate to protest on the Standing Rock Indian Reservation. An affidavit says more than 100 demonstrators, many with their faces covered, halted construction and vandalized equipment.