The criminal trial of the man accused of trying to assassinate US President Donald Trump got off to a contentious start as a federal judge cut off a meandering opening statement from defendant Ryan Routh.

Florida-based US District Judge Aileen Cannon stopped Routh's presentation to a jury after only a few minutes after Routh delved into topics including the origin of the human species, the settlement of the American West, and international conflicts.

Cannon had earlier warned Routh that she had limited patience for an argument that would "make a mockery of the dignity of the courtroom."

Routh, 59, has pleaded not guilty to five federal charges, including attempted assassination of a major presidential candidate. He faces a maximum sentence of life in prison.

The trial began the day aft

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