Dallas surgeon Randall Kirby says his former colleague, Dr. Christopher Duntsch, managed to commit crimes so heinous that patients everywhere are still struck by fear when they hear about the case for the first time.

“He couldn’t operate at all,” Kirby told Fox News. “That led me to believe he was a sociopath or a psychopath, something of that sort. … I’ve been in the business for decades and this guy is not normal. He turned his best friend into a quadriplegic.”

Wondery, the podcast network behind the hit true crime series “Dirty John,” recently launched the story of “Dr. Death,” the true story of Dr. Duntsch, a neurosurgeon whose horrifying deeds continue to haunt Texas.

The 47-year-old doctor operated on a total of 38 patients, and 31 of them were left permanently paralyzed or seriously injured. Two others died.

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“Dr. Death” features interviews with Kirby, who first reported him to the authorities, as well as those who knew and worked with Duntsch over the years.

Between 2011 and 2013, Rolling Stone previously reported, Duntsch was employed by four Dallas-area hospitals and nearly all of his patients, those who survived, came out in far worse shape than ever before.

In 2017, a jury sentenced Duntsch to life in prison for maiming patients who had turned to him for surgery to resolve debilitating injuries. The decision came almost a week after the Dallas County jury convicted Duntsch of first-degree felony injury to an elderly person.

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Kirby assisted on one of Duntsch’s surgeries in 2012, as The Texas Observer previously reported, and he said he performed “horribly” and was so "clueless.”

"... He’d always talked about himself and how great he was," Kirby told Fox News. "But he was saying it in front of people who were giants in spine surgery. … These were giants who published papers and took on cases that no one else would do. And so in the middle of a doctor’s lounge, this guy would prance in and tell everyone how great he was. … I just thought he was off.”

Kirby said he immediately became alarmed when he realized Duntsch had “no spatial relationship skills at all” and struggled in the operating room. Kirby claimed Duntsch couldn’t move organs and blood vessels out of the way properly and nicked a patient’s vertebral artery, resulting in a pool of blood to form.

According to the Texas Observer, the patient, Barry Morguloff, woke up with agonizing back pain and had no feeling in his left leg. Scans later revealed bone fragments from his vertebrae were reportedly lodged in the nerves of his back.

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Three weeks later, Duntsch performed surgery on childhood friend Jerry Summers, which resulted in Duntsch slicing into an artery, resulting in bleeding and seriously damaging Summers’ spinal cord. The publication shared Duntsch attempted to stop the bleeding by packing coagulants around the wound. When Summers woke up, he couldn’t move his arms or legs.

Later in the trial, Kirby told jurors he sent information to the Texas Medical Board, warning them of Duntsch’s botched surgeries. D Magazine shared that despite receiving complaints dating back to 2012, the Texas Medical Board reportedly didn’t revoke Duntsch’s privileges until 2013. Texas Observer clarified that the Texas Medical Board is "limited" in its ability to investigate malpractice, which could have possibly resulted in the delay.

"For one thing, it can open a case only if it receives a written complaint — akin to a police department that forbids its officers from investigating criminal activity they witness," claimed the publication. "With the exception of pain management clinics and anesthesiologists, the board doesn’t have the authority to inspect a doctor, or to start an investigation on its own."

Wondery confirmed to Fox News two former members of the Texas Medical Board also participated in the podcast to weigh in.

That same year, Kirby helped bring the case to prosecutors and asked to press charges.

“It took me a year to convince the district attorney’s office to take the case, that he needed to be investigated for attempted murder and that’s what they did,” claimed Kirby. “What was horrifying was that he kept doing it. … He kept making the same mistakes over and over again, not recognizing that he needed to stop operating. … He kept moving from hospital to hospital, and he kept being granted privileges to operate. I’ve made all my feelings known in the local and national press about that.”

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According to records, Duntsch was booked into the Dallas County Jail in 2015. He was charged with five counts of aggravated assault causing serious bodily injury and one count of injury to a child, elderly or disabled person.

“The wheels of justice turn slowly, but apparently they still turn,” wrote James Girards, a plaintiff’s attorney, in a statement on his firm’s website. “It still remains to be seen who else will go to jail for allowing Duntsch to run amock in the operating room.”

Girards claimed Duntsch was allowed to operate on the spines of patients despite his “background of abuse of cocaine, LSD, hydrocodone and alcohol.” Girards also alleged that according to witnesses, Duntsch “had a gallon jug of vodka under his desk,” “swiped his surgical assistant’s narcotics” and “a bag of white powder was found in a baggie in his office bathroom.”

While Kirby said he wouldn’t be surprised if Duntsch was under the influence, he himself never witnessed drugs or alcohol around the medical madman.

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“No one ever smelled alcohol on his breath in the operating room,” said Kirby. “So it’s hard for me to make the case that he was impaired. … I never got that kind of report from the nursing staff.”

D Magazine reported that in July 2016, the Dallas County District Attorney’s Office followed through and a grand jury returned five indictments of aggravated assault and one of harming an elderly person. Duntsch pleaded not guilty and alleged in emails that he was at the center of “a vast conspiracy to bilk money from the hospitals where he practiced.”

The indictment accused Duntsch of wide-ranging malpractice, including improper placement of screws and plates along patients’ spines, a sponge left in one patient, and a major vein cut in another. Records also showed that Duntsch operated on the wrong part of a patient’s spine, damaged nerves and left one woman with chronic pain and dependent on a wheelchair.

At the time, Duntsch was struggling financially and had racked up a series of arrests, including stealing Walmart merchandise.

Kirby said he was determined to do whatever possible to ensure Duntsch never harmed another patient again.

“He took his friend’s head and destabilized it so bad it was falling off,” he said.

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During the trial, prosecutors said Duntsch’s hands and surgical tools amounted to “deadly weapons,” and contended that he “intentionally, knowingly and recklessly” harmed up to 15 of his patients. Prosecutors also claimed that in a 2011 email to a girlfriend, Duntsch said he would “become a cold-blooded killer.”

However, Duntsch’s attorneys argued that he was not a criminal but just a lousy surgeon committing malpractice in chaotic operating rooms in hospitals in Dallas and its northern suburbs. They also said the tone of the email in question was unclear and could have been meant as sarcasm.

Kirby said he has no doubt in his mind Duntsch is a serial killer.

“He basically was, because he kept doing the same thing wrong over and over again, hurting people,” he explained. “And [most] doctors are going to do that, they’re just going to stop operating. It’s just too traumatic for them. … I just couldn’t believe this guy slipped into training.”

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The New Yorker reported Duntsch was ultimately stopped after the combined involvement of the Dallas Country district attorney, an attorney, a journalist, and the state medical board with the efforts initiated by Kirby and Dr. Robert Henderson, a veteran surgeon at the Dallas Medical Center.

Kirby hopes the podcast will encourage listeners to conduct no-nonsense research on any physician they’re considering.

“The most important thing you can do is investigate who you’re allowing to operate on you,” he said. “No one is touching my spine unless I have seven, eight people who can say the surgery went well. I’m hoping patients are much more cautious and that they get second, third opinions. The consumer has to be aware of what’s going on. This is a cautionary tale for everybody.”

"Dr. Death" is currently available for streaming on Wondery. The Associated Press contributed to this report.