The medical examiner who examined Jordan Neely’s body after Daniel Penny held him on an uptown F train last year could identify no other reasonable explanation for his death other than neck compression, she testified during the trial Penny’s Criminal Court in Manhattan on Friday.

“Is it your opinion that if Mr. Neely’s neck had not been compressed, he would not have died?” asked Assistant District Attorney Dafna Yoran.

“Yes,” replied Dr. Cynthia Harris of the Office of the Chief Coroner.

Harris’ testimony Friday is critical for prosecutors, who must establish that Penny caused Neely’s death. She was the final witness in the prosecution’s case. Penny’s defense attorneys are expected to call their own witnesses starting Monday.

Penny has pleaded not guilty to charges of involuntary manslaughter and criminally negligent homicide in Neely’s death. On May 1, 2023, Penny wrapped her arm around Neely’s neck, pulled him to the floor of the train and continued to hold her for about six minutes, according to evidence in his trial. Neely was pronounced dead at a hospital a short time later. Penny told the detectives that he choked Neely because he was yelling threats and “acting like a lunatic.” He also said he was trying to detain Neely until police arrived at the next station — not kill him.

But Harris said the suffocation prevented oxygen from reaching Neely’s brain, causing him to lose consciousness and eventually die. She said the oxygen was probably cut off in part by pressure on one side of Neely’s neck. Oxygen flow could also have been blocked by pressure under Neely’s chin, which the coroner said could have pushed Neely’s tongue or other tissue into his throat. She added that this type of lock would only require a small amount of force.

Over the course of about four hours Thursday and Friday, Harris walked jurors through some of the body’s mechanisms, explaining in detail how people breathe and what can happen if airflow is obstructed. She showed diagrams from textbooks and explained medical terms such as hemorrhage and capillaries. As jurors watched videos of the incident, she pointed out moments in Neely’s appearance that suggested his body was starved for oxygen — such as his abdomen rising and falling, his face turning purple and veins bulging. The medical examiner also noted pools of fluid that had formed on Neely’s pants, which she said were likely urine excreted during the process of death.

As videos and photos of the suffocation played on screens in the courtroom, Neely’s father buried his head.

Harris also reviewed images of Neely’s body from the autopsy and pointed out the damage he observed. She noticed bleeding inside his neck and pools of blood in his eyes. Jurors also looked at photographs of Neely’s neck, which showed red scratch marks. Harris said they were likely self-inflicted because Neely tried to pull Penny’s arm off.

Penny’s defense attorneys sought to cast doubt on Harris’ assessment, arguing in their opening statement that Neely could have died from synthetic cannabinoids in his system or a condition he called sickle cell trait.

Harris said he did not believe any of these could have caused Neely’s death. She said the synthetic cannabinoids — which are stimulants — likely killed Neely through a cardiac arrhythmia, cutting off blood to the heart. She said that would have closed Neely’s heart almost immediately. But Neely continued to have a pulse even after he voluntarily stopped moving, according to a man who held Neely’s arms and the police who intervened on the scene. The coroner said this suggested his heart continued to work even after his brain was deprived of oxygen.

The sickle cell trait, Harris said, is usually benign. She said compression of the neck could have caused Neely’s cells to sequester, meaning they became misshapen and couldn’t transport blood properly. But she said that would have been a result of suffocation.

During cross-examination, defense attorney Steven Raiser asked Harris if an intense struggle could have caused Neely’s death, even if Neely had not been suffocated. He questioned whether other factors could have weakened Neely’s heart, such as his schizophrenia and frequent use of synthetic cannabinoids and cigarettes. The attorney also questioned why Harris ruled Neely died of asphyxiation before receiving all test results.

The coroner said the cause of death became clear once he watched a video of the suffocation and its aftermath.

“After watching her, I had no more questions about why she died,” she said.

Harris testified that she presented her findings to other medical examiners, including the chief, and everyone unanimously agreed with her assessment.

“No toxicology report would have changed my mind,” she said.