The trial of former Minneapolis police officer Derek Chauvin, who killed George Floyd when he pressed his knee into his neck last summer, began Monday with the proceedings being broadcast live in an unprecedented first for the state of Minnesota.

Chauvin has entered a plea of not guilty to second-degree unintentional murder, third-degree murder and second-degree manslaughter charges, The New York Times reports.

In presenting the harrowing footage of the final moments of Floyd's life, prosecutors say Chauvin unintentionally killed Floyd while exerting an excess of force during an arrest on May 25, 2020. According to the news station WRCB TV, Chauvin’s team aims to argue that Floyd’s death was attributed to drug use and other unrelated medical issues. Defense attorneys have also contended that Chauvin was abiding by proper police procedures during the May encounter.

The historic trial will center around specific details regarding the case, which includes Floyd's autopsy, the former police officer’s mindset and finding clarity in legal terms such as "depraved mind" and "culpable negligence."

The trial will take place at the Hennepin County courthouse, a highly secure location in Minneapolis. Due to pandemic precautions, plexiglass walls have been set up inside the courtroom, and witnesses and lawyers have been instructed to wear face masks.

Here are some of the takeaways from day one of the trial.