Trump assassination suspect pleads not guilty

The suspect's first court appearance saw his legal team argue that Allen was suffering from a mental health crisis and did not have a coherent plan to harm the president.

Prosecutors, however, presented evidence of extensive planning and social media posts detailing a desire to commit an act of political violence.

The incident has led to a significant increase in security protocols for presidential events and a renewed debate over the rise of domestic extremism.

Allen remains held without bail as he awaits a trial that could see him face life in prison.