The Colorado Attorney General’s office finished putting on its case Friday in the prosecution of Nathan Woodyard, the third Aurora police officer on trial in connection with Elijah McClain’s death.

As their final witness, prosecutors called Roger Mitchell, a forensic pathologist who characterizes McClain’s death was a homicide.

Mitchell has provided perhaps the most definitive opinion of all the medical experts called by prosecutors that the struggle with police contributed to the 23-year-old man’s death. Spending most of Friday on the witness stand, he said he believes McClain’s death resulted from complications of the ketamine injection he received during “violent subdual and restraint.”

“If that violent restraint and subdual doesn’t happen, I believe he’s continuing to walk home and he’s alive today,” Mitchell said.

Mitchell serves as the chair of pathology at the Howard University College of Medicine and is also a former chief medical examiner for Washington, D.C. His opinion that McClain’s death was a homicide stands in contrast to that of the forensic pathologist who performed McClain’s autopsy. Stephen Cina, who testified last week, has maintained his manner of death as “undetermined.”

Woodyard faces charges of reckless manslaughter and criminally negligent homicide in connection with McClain’s death. He was the first officer to contact McClain the night of Aug. 24, 2019 as the 23-year-old walked home from a convenience store. He and two other officers, Jason Rosenblatt and Randy Roedema, responded to a 911 call by a teenager who believed McClain looked “sketchy” after he saw McClain wearing a black mask and waving his arms. He was listening to music and often wore a face mask to keep warm, prosecutors say.

A few minutes into the encounter, Woodyard used a neck hold on McClain known as a carotid hold, which temporarily restricts oxygen to a person’s brain and can induce brief unconsciousness. Mitchell testified he believes the carotid hold kicked off a cycle of increased acid buildup in his blood as he labored to breathe, causing him to vomit and then inhale it into his lungs — called aspiration — because he couldn’t clear his airway while on the ground.

“He’s coming out of being unconscious in an environment where he still has an altercation that’s happening. And so you can hear the distress, and then you can hear his labored breathing,” Mitchell said.

He watched body-worn camera footage of the struggle in segments and testified about how he believes McClain’s condition deteriorated.

Woodyard, Roedema and Rosenblatt took McClain to the ground when he initially tried to keep walking, appearing confused by the stop. Roedema said several times during the struggle he saw McClain try to grab Rosenblatt’s gun, body-worn camera footage shows. It appears Woodyard used the carotid hold shortly after Roedema first made that statement, though prosecutors deny McClain actually reached for a gun.

A paramedic called to the scene later injected McClain with a 500-milligram dose of ketamine, a sedative. He stopped breathing and went into cardiac arrest shortly after and was pronounced dead in a hospital three days later.

Woodyard’s defense attorneys argue he had to adapt quickly during the encounter without the benefit of hindsight, and that the carotid hold was actually his attempt to use non-lethal force to de-escalate the situation. They also say he stepped away from the immediate area for much of the encounter after he applied the carotid hold and was not within hearing distance of the struggle for that time.

During cross-examination of Mitchell, defense attorney Megan Downing sought to sow doubt that it’s possible to pinpoint a moment during the struggle with police officers that set off McClain’s deterioration. She also pressed Mitchell on his opinion that he couldn’t say for certain whether McClain would have died without the ketamine injection.

“You have said that you cannot state, and you have not stated, that Mr. McClain would have died only from the police encounter. Is that consistent with what you’re telling us today?” Downing asked.

“That’s correct,” Mitchell said.

His attorneys also seek to lay blame instead on Aurora Fire Rescue paramedics, because of their decision to give McClain the ketamine injection without examining or talking to him. Paramedics Jeremy Cooper and Peter Cichuniec also face charges for McClain’s death and have a trial scheduled to start next month.

Jurors will return Tuesday for the remainder of Woodyard’s trial.