In a testament to the horrors of George Floyd's murder, the trial of the former Minneapolis police officer who killed him, Derek Chauvin, has produced several emotionally devastating moments since it began just this Monday.

Yesterday saw another sad chapter in this awful story when Charles McMillian, who witnessed Floyd's murder firsthand, broke down in tears while watching body camera footage of the event.

McMillian was so overwhelmed that Judge Peter Cahill had to call a brief recess.

Chauvin is on trial for second-degree unintentional murder, third-degree murder and second-degree manslaughter after kneeling on George Floyd's neck on the pavement outside a store for nine minutes last Spring while Floyd begged for air and pleaded for his deceased mother.

McMillian was driving by the incident last May and decided to stop because, as he told the jury, "I'm a nosy person." He saw Chauvin and other officers confronting Floyd and urged him to go with the officers willingly to avoid being injured.

In bodycam footage, McMillian was heard telling Chauvin, after Floyd's body had been removed by emergency responders, that his degree of force was unnecessary.

Chauvin replied:

"That's one person's opinion. We had to control this guy because he's a sizable guy. It looks like he's probably on something."

When prosecutors played footage of Floyd's death, McMillian was overwhelmed. By the end he was weeping, saying he felt "helpless" watching Floyd die.

Floyd's calls for his mother in particular seemed to upset McMillian the most.

He testified:

"I don't have a mama either―I understand him."

McMillian's testimony also gave a bracing account of the physical brutality Chauvin inflicted on Floyd:

"He appeared to be in and out [with] white foam running out of his mouth."

Tellingly, Chauvin's defense team chose not to cross-examine McMillian.

McMillian is just one of several witnesses who have been overcome with emotion during their testimony on Floyd's murder. Another witness described staying up at night "apologizing and apologizing" to Floyd for not having been able to save him.

McMillian's testimony has sparked outrage and sadness in many people online.

If convicted, Chauvin faces up to 40 years in prison, though is expected to serve only 10 to 15 under Minnesota sentencing guidelines.