MINNEAPOLIS (WCCO) — A man who is accused of killing his mother and nephew using a samurai sword last year has been found incompetent to stand trial.

Ishmael Roberts, 22, is charged with killing 57-year-old Beatrice Wilson, his mother, and then turning the sword on his 14-year-old nephew Peter Wilson last October.

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Roberts was arrested a day later in Waterloo, Iowa after crashing a stolen car in the city.

The complaint against Roberts says he replaced his blood-covered shoes at a Waterloo Target store. Store cameras clearly show him tossing the bloody shoes in a dumpster, along with the car’s blood-covered floor mat.

At the time of the killings, Roberts declined to talk about his motivation in the violent acts he was accused of perpetrating.

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“We asked him one question — what was this about with your family? He said as is his constitutional right, ‘I don’t want to talk,'” Hennepin County Attorney Mike Freeman said. “We may never know.”

On Tuesday, Roberts was found incompetent. An examiner will be appointed by the courts to determine whether civil commitment is appropriate.

Roberts will also have the opportunity to request a second examiner.

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A hearing will be scheduled ever six months to review Roberts’ competency. His next hearing is scheduled for Sept. 19.