Key takeaways from the Derek Chauvin trial in George Floyd's death, as jurors near deliberation

The jury in the trial of former Minneapolis police officer Derek Chauvin in the death of George Floyd has now heard nearly three weeks of at-times emotional testimony from over three dozen witnesses, as well as watched hours of video of Floyd's arrest.

The court proceedings continue Monday morning with closing arguments from the prosecution and defense and final instructions for the jury, which will be sequestered while they deliberate to reach a verdict.

Chauvin, 45, faces second-degree unintentional murder, third-degree murder and second-degree manslaughter charges in the death of Floyd, 46.

Here are some of the major takeaways from the high-profile trial after 14 days of evidence.

Chauvin, Hall invoke 5th Amendment

A question throughout the trial had been whether Chauvin would testify in his own defense. On April 15, the last day of testimony, that question was answered. Before the jury entered the courtroom and the defense wrapped its case, Chauvin addressed the court to say he would invoke his Fifth Amendment privilege.

The decision came after several conversations with his attorney, Eric Nelson, including a long one the night before, Nelson said.

When asked by Hennepin County Judge Peter Cahill if he was pressured into making the decision, Chauvin responded, "No promises or threats, your honor."

Cahill said he will comply with Chauvin's request to instruct the jury that they "should not draw any inference" on his guilt or innocence by exercising his right not to testify.

Chauvin wasn't the only one to invoke the Fifth Amendment. The day before, Morries Hall, who was in a vehicle with Floyd the day he died, said he wanted to invoke the Fifth Amendment to avoid any incriminating testimony.

"I'm fearful of criminal charges going forward. I have open charges that's not settled yet," Hall said.

Hall has been identified during trial testimony as a suspected drug dealer from whom Floyd obtained narcotics.

Medical witnesses testify Floyd died of asphyxia

The prosecution has argued that Floyd died because of restraints by police officers, including Chauvin's knee pressed down on his neck during the arrest.

Floyd's autopsy report concluded that he died of "cardiopulmonary arrest, complicating law enforcement subdual, restraint, and neck compression," meaning that his heart and lungs stopped working. It did not specifically mention asphyxia.

However, several medical witnesses testified that Floyd did die by asphyxia, among them world-renowned pulmonologist Dr. Martin Tobin, a Chicago doctor and breathing expert.

While testifying on April 8, he led jurors through a series of demonstrations illustrating the pressure placed on Floyd's neck during the arrest, concluding he died from "a low level of oxygen" that damaged his brain and stopped his heart. With Chauvin's knee on his neck, Floyd was essentially squeezed to death, he said.

"A healthy person subjected to what Mr. Floyd was subjected to would have died," Tobin said.

During her testimony the following day, Dr. Lindsey Thomas, a forensic pathologist in Minneapolis, supported Tobin's statements that Floyd died of asphyxia. She said she reached that conclusion by watching footage of the arrest.

"In this case, the autopsy itself didn't tell me the cause and manner of death," she said. "In this case, it was primarily the evidence from the terminal events, the video evidence, that show Mr. Floyd in a position where he was unable to adequately breathe."

When Dr. Andrew Baker, the Hennepin County medical examiner who conducted Floyd's autopsy, took the stand earlier that same day, he said he didn't look at video of Floyd's arrest until after completing the report. He told jurors he believes the main cause of death was law enforcement restraint.

When the defense questioned Baker on the lack of bruises on Floyd's neck and back, the doctor said, "That's just not something that I think we see as medical examiners -- pressure to the back of the neck explaining strangulation."

Defense tries to sow reasonable doubt Floyd died due to police restraints

While the prosecution argued that Floyd died due to police restraints used during his arrest, the defense countered that Floyd's heart disease and drug use -- fentanyl and methamphetamine were found in his system during an autopsy -- played a role in his death.

A medical expert presented by the defense, Dr. David Fowler, said Floyd's heart condition, drug use and a potential stomach tumor played a "significant" role in his death.

He also brought up another potential contributing factor not yet presented -- carbon monoxide exposure, from the tailpipe of a nearby police car while Floyd was pinned to the ground.

"They contributed to Mr. Floyd having a certain cardiac arrest, in my opinion. That's how I would read it," said Fowler, who added that Floyd's blood was not tested for carbon monoxide.

Fowler, a former Maryland chief medical examiner, testified that if he were the medical examiner in the case, he would have classified the death as "undetermined," not homicide.

Police officials say Chauvin violated policies

A dozen current and former members of law enforcement testified for the prosecution that Chauvin violated numerous police use-of-force and ethics policies and training while detaining Floyd.

Among them was Minneapolis Police Department Chief Medaria Arradondo, who testified on April 5 that the former officer violated the force's underlying motto to "protect with courage and serve with compassion."

He also said Chauvin, as well as the other officers who restrained Floyd, failed to provide first aid even though they had checked for a pulse and not found one.

Lt. Richard Zimmerman, who has the most seniority of any officer in the Minneapolis Police Department, called the use of force used on Floyd "totally unnecessary" during his testimony on April 2.

Meanwhile, Barry Brodd, a consultant on police practices and use of force who testified for the defense on April 13, told the jury that Chauvin "was acting with objective reasonableness following Minneapolis Police Department policy," and that his use of force was "appropriate" and not deadly.

He said he didn't consider placing Floyd in the prone position a use of force, though conceded during cross-examination that if officers inflict pain on a person being held in that position, it could constitute a use of force.

Floyd's brother provides 'spark of life doctrine' testimony

Minnesota, unlike many states, allows loved ones of an alleged crime victim to testify in advance of a verdict, as opposed to leaving it for victim impact statements during sentencing if there is a conviction.

George Floyd's younger brother, Philonise Floyd, gave what's known in the state as "spark of life doctrine" testimony on April 12.

It was during that testimony that jurors learned about George Floyd, beyond his drug addiction and the circumstances of his death.

"This puts some personal nature back into the case for somebody who's treated so impersonally in an unfortunately biased system," prosecutor Matthew Frank told Cahill.

At times wiping away tears, Philonise Floyd spoke of his brother's love of their late mother, Larcenia Floyd, whom George Floyd cried out for while being pinned by Chauvin.

Philonise Floyd called his brother a "big momma's boy" and shared a photo of him as a child being held by their mother.

"Being around him, he showed us, like, how to treat our mom and how to respect our mom. He just -- he loved her so dearly," Philonise Floyd said.

ABC News' Bill Hutchinson, Marlene Lenthang and Whitney Lloyd contributed to this report.