A medical examiner called to the stand in the manslaughter trial of Daniel Penny, who is accused of fatally choking a homeless man on the New York subway, said there was insufficient evidence that choking caused the death the victim.

Dr. Satish Chundru, who was called to testify by Penny’s attorneys, blamed Jordan Neely’s death on a combination of a sickle cell crisis and the effects of synthetic marijuana.

Neely, 30, who had confronted those aboard an F train, was pronounced dead at the scene after Penny, 26, restrained him last May.

The medical examiner ruled the death a homicide — a determination Chundru aggressively disputed Thursday.

Chundru of Texas argued that someone like Neely, who was schizophrenic, tall and involved in a fight, could die without the airway being restricted.

The former Miami-area coroner’s statement was in stark contrast to that given days earlier by the city’s coroner.

Dr. Cynthia Harris had argued that neither drugs nor the victim’s genetic disorder took Neely’s life, while also ruling out cardiac arrest.

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A forensic pathologist called to the stand in the manslaughter trial of Daniel Penny, who is accused of using a fatal chokehold on a homeless man on the New York subway, said there was insufficient evidence that a chokehold caused the death the victim.

The expert blamed Jordan Neely’s death on a combination of a sickle cell crisis and the effects of synthetic marijuana.

“Suffocation did not cause death,” said Dr. Chundru in court Thursday after defense attorney Steven Raiser asked for his opinion on the matter.

He said Neely died from the “combined effects” of synthetic marijuana, schizophrenia and blood conditions that can lead to fatal complications during exertion.

He went on to describe how in a suffocation death there are two phases: unconsciousness and death.

Pointing to video taken by passengers on the train, he argued that a visibly struggling Neely was not first knocked unconscious and actually died instantly.

“What is … important is that unconsciousness always follows death in a suffocation,” he said.

“This is a very complicated case,” Chundru continued. “We’ve got schizophrenia involved, sickle cell trait involved, a suffocation.

“In a sickle cell crisis, death is a lack of oxygen,” he explained. “So the same thing (in a death by asphyxiation.”

Chundru added that a victim who loses consciousness due to the restriction of air passage would not necessarily lead to death.

Dr. Satish Chundru made the claim in Manhattan Criminal Court on Thursday. He is seen here testifying during another case in 2012

A former Marine, Penny had headed to a gym after attending a college class. He is charged not only with manslaughter, but with manslaughter

The suffocated person, after being freed, usually woke up, he said.

Footage from the incident shows Penny, a former Marine whose former instructor testified in court last week, holding a choke hold after Neely unleashed.

The prosecution had already rested its case on Monday morning, allowing the defense to present its arguments.

Prosecutors painted Penny as unqualified, saying he improperly administered a chokehold for a period that led to the victim’s death.

Meanwhile, Penny admitted that she had no formal jiu-jitsu training other than what she was given while training to be a Marine.

Last Thursday, the Marine who trained Penny to apply a chokehold, combat instructor Joseph Caballer, admitted that witness video showed his former cadet appeared to have done it incorrectly.

Caballer testified that the video appeared to show Penny trying to use a “blood choke” to restrain Neely — something she said should have seen him unconscious within seconds.

Instead, the detention lasted more than six minutes.

Prosecutors painted Penny as unqualified, saying he improperly administered a chokehold for a period that led to the victim’s death.

Penny admitted that she had no formal training in jiu-jitsu, other than what she was given while training to be a Marine.

The Marine who trained Penny to apply a chokehold, Combat Instructor Joseph Caballer, acknowledged that the video shot by witnesses indicated that his former cadet appeared to have administered the chokehold improperly.

Dr. Chundru argued that someone like Neely, who was schizophrenic, tall and involved in a fight, could die without the airway being restricted.

During that time, Neely, while squirming in Penny’s arms, may have inadvertently turned the squeeze into an “air choke,” which takes longer to render a person unconscious and could prove fatal much easier.

Mastery is not taught by Marines, he told jurors.

The prosecution will have the opportunity to challenge Chundru’s opinion during the interrogation.

Penny, 26, is charged with involuntary manslaughter and involuntary manslaughter. He faces up to 15 years in prison.