(CNN) What was going through Derek Chauvin's mind when he kneeled on a handcuffed, prone George Floyd for nine minutes and 29 seconds last May?
That key question was at the heart of the three charges against the former Minneapolis Police officer and was top of mind for jurors in their deliberations. To render a verdict, they also had to interpret Minneapolis Police policies, Floyd's cause of death, and the specific language of the law.
The jury found Chauvin, 45, guilty of all three charges -- second-degree unintentional murder, third-degree murder and second-degree manslaughter. He could face up to 40 years in prison for second-degree murder, up to 25 years for third-degree murder, and up to 10 years for second-degree manslaughter.
The actual sentences would likely be much lower, though, because Chauvin has no prior convictions. Minnesota's sentencing guidelines recommend about 12.5 years in prison for each murder charge and about four years for the manslaughter charge. The judge would ultimately decide the exact length and whether those would be served at the same time or back-to-back.
The second-degree unintentional murder charge alleged Chauvin caused Floyd's death "without intent" while committing or attempting to commit felony third-degree assault. In turn, third-degree assault is defined as the intentional infliction of substantial bodily harm.
The third-degree murder charge alleged Chauvin caused Floyd's death by "perpetrating an act eminently dangerous to others and evincing a depraved mind, without regard for human life."
The second-degree manslaughter charge alleged Chauvin caused Floyd's death by "culpable negligence whereby the person creates an unreasonable risk, and consciously takes chances of causing death or great bodily harm."
Each of the three charges required prosecutors to prove that Chauvin's actions were not objectively reasonable and that they were a substantial cause of Floyd's death. But the charges differ primarily in how they interpret his intent and mindset during his restraint of Floyd.
Some of the terms in these charges have specific definitions. Others were left up to the jury to interpret.
As in any criminal case, the prosecution had the burden of proof and had to prove the charges beyond a reasonable doubt.
Central to all of the charges is the element of causation, or that Chauvin was a substantial causal factor in Floyd's death.
To prove that point, prosecutors featured testimony from five doctors who said that Floyd died of insufficient oxygen due to Chauvin's restraint of a handcuffed Floyd in the prone position -- known as "positional asphyxia."
Hennepin County Medical Examiner Dr. Andrew Baker, who conducted Floyd's autopsy, testified that the police subdual and restraint was his primary cause of death. Yet he also listed Floyd's arteriosclerotic and hypertensive heart disease, fentanyl intoxication and methamphetamine use as significant conditions.
Other medical experts for the prosecution were more definite.
"A healthy person subjected to what Mr. Floyd was subjected to would have died," said Dr. Martin Tobin, a pulmonologist and critical care doctor who explained the physiology of breathing.
The defense tried to undermine that by highlighting Floyd's drug use and underlying heart issues. They suggested he died during the restraint -- but not because of Chauvin's actions.
Dr. David Fowler, Maryland's former chief medical examiner, testified for the defense that Floyd's cause of death should have been classified "undetermined," saying his underlying heart issues were the main causes.
"In my opinion, Mr. Floyd had a sudden cardiac arrhythmia, or cardiac arrhythmia, due to his atherosclerosis and hypertensive heart disease ... during his restraint and subdual by the police," he said.
Secondly, all of the charges required prosecutors to prove that Chauvin used excessive and unreasonable force, contrary to his police training.
To prove that point, a handful of police supervisors and use-of-force experts criticized Chauvin's kneeling on Floyd, who was not resisting and was unconscious for several minutes of the restraint.
In particular, Minneapolis Police Chief Medaria Arradondo thoroughly rejected Chauvin's kneeling on Floyd's neck, saying it "in no way, shape or form is anything that is by policy. It is not part of our training, and it is certainly not part of our ethics or our values." He said Chauvin violated policies around de-escalation, objectively reasonable use of force and requirement to render aid.
The defense, meanwhile, argued Chauvin's actions looked ugly to bystanders but were within his proper training. They portrayed his knee on Chauvin's neck and back as a common ground control technique.
Barry Brodd, a use-of-force expert testifying for the defense, said Chauvin was justified in kneeling on Floyd for over nine minutes and did not use deadly force.
"I felt that Derek Chauvin was justified and was acting with objective reasonableness, following Minneapolis Police Department policy and current standards of law enforcement in his interactions with Mr. Floyd," said Brodd, a former police officer.
The three charges each interpret Chauvin's intent last May in a slightly different way.
The second-degree unintentional murder charge is what's known as felony murder, or when a person commits an underlying felony and someone unintentionally dies. This charge required the jury to find that Chauvin intended to assault Floyd and inflict substantial bodily harm.
The third-degree murder charge alleged that Chauvin had a "depraved mind, without regard for human life." The basic gist of depraved mind is "extreme recklessness," according to Richard Frase, Professor of Criminal Law at University of Minnesota Law School.
The charge is generally used in cases where a person drives a vehicle the wrong way or fires a weapon into a crowd. This murder charge was dismissed by the judge last year but reinstated in March after an appeals case involving the murder conviction of former Minneapolis Police officer Mohamed Noor.
Finally, the second-degree manslaughter charge relies on "culpable negligence," which has been interpreted to mean gross negligence combined with recklessness.
Chauvin invoked his Fifth Amendment right not to testify in his own defense. So to get inside his head, jurors instead had to rely on the totality of the evidence, including videos of Chauvin on Floyd as well as his comments immediately afterward defending his actions.
For example, in a rebuttal to the defense's closing arguments, prosecuting attorney Jerry Blackwell told the jury to note Chauvin's body language.
"This wasn't the face of fear or concern or worry," he said.
The defense also had argued that Chauvin behaved the way he did because he was distracted by a hostile crowd of bystanders. Chauvin may not have done exactly as trained, this theory goes, but the crowd's hostility offers a non-criminal explanation why.
However, the bystanders testified that nobody threatened the officers and that they raised their voices only because Floyd appeared to be in an increasingly dire condition. Further, a Los Angeles Police Department sergeant and use-of-force expert for the prosecution testified that he doesn't believe Chauvin was distracted because he was interacting directly with what Floyd was saying.