I didn't pay much attention to the courtroom proceedings in the last few weeks but evidently, the jury believed the presented evidence cleared the bar for the 2nd and 3rd degree murder charges.
2nd degree murder:
It's also called felony murder. To prove this count, prosecutors had to show that Chauvin killed Floyd while committing or trying to commit a felony - in this case, third-degree assault. They didn't have to prove Chauvin intended to kill Floyd, only that he intended to apply unlawful force that caused bodily harm.
Prosecutors called several medical experts who testified that Floyd died from a lack of oxygen because of the way he was restrained. A use of force expert said it was unreasonable to hold Floyd in the prone position for 9 minutes, 29 seconds, handcuffed and face-down on the pavement.
"No reasonable officer would have believed that that was an appropriate, acceptable or reasonable use of force," prosecution witness Seth Stoughton testified."
3rd degree murder:
"For this count, jurors must find Chauvin caused Floyd's death through an action that was "eminently dangerous" and carried out with a reckless disregard for and conscious indifference to the loss of life.
Mark Osler, a professor at University of St. Thomas School of Law, said prosecutors tried to prove the elements of this count through testimony about the dangers of subduing a handcuffed person in the prone position.
Dr. Martin Tobin, a lung and critical care specialist, testified for the prosecution that any healthy person subjected to this restraint would have died. Minneapolis Police Lt. Johnny Mercil, a use-of-force instructor, testified that officers are trained to "stay away from the neck when possible." Osler said Police Chief Medaria Arradondo was also effective in showing that Chauvin was not trained to use such a hold.
"They wanted to have a lot of evidence showing that what Chauvin did is not what he was trained to do and that the reason they don't train people to do that is because it's eminently dangerous," Osler said."
3rd degree manslaughter:
"
Prosecutors had to show that Chauvin caused Floyd's death through culpable negligence that created an unreasonable risk, and that he consciously took the chance of causing severe injury or death.
Testimony that revealed Chauvin should have known to put Floyd in a side recovery position, that he should have provided medical care before paramedics arrived and that he stayed in his position after he was told Floyd didn't have a pulse could all point to negligence, said former U.S. Attorney Tom Heffelfinger."
From what I did read, the defense tried to counter each of those testimonies, but evidently didn't do a very good job of it.
