(Mark Ralston/Agence France-Presse/Getty Images)

Like a lot of other doctors, child welfare advocates and forensic specialists, John Plunkett at first bought into the theory of Shaken Baby Syndrome (SBS). This is the theory that an autopsy on a young, recently deceased child reveals three symptoms — bleeding in the back of the eyes, brain swelling, and bleeding in the subdural space just above the brain — those injuries could only have been caused by violent shaking. The diagnosis gained popularity in the 1990s, then became more common still after the high-profile trial and conviction of British nanny Louise Woodward in 1997.

It’s a convenient diagnosis for prosecutors, in that it provides a cause of death (violent shaking), a culprit (whoever was last with the child before death) and even intent (prosecutors often argue that the violent, extended shaking establishes mens rea.) According to a 2015 survey by The Washington Post and the Medill Justice Project, there were about 1,800 SBS prosecutions between 2001 and 2015, with 1,600 resulting in convictions.

But in the late 1990s, Plunkett — a forensic pathologist in Minnesota — began to have doubts about the diagnosis. He started investigating cases in which children had died in a manner similar to the way accused caregivers had described the deaths of the children they were watching — by short-distance falls. What he found alarmed him. In 2001, Plunkett published a study detailing how he had found symptoms similar to those in the SBS diagnosis in children who had fallen off playground equipment. It was a landmark study. If a short-distance fall could produce symptoms similar to those in SBS cases, the SBS diagnosis that said symptoms could only come from shaking was wrong. By that point, hundreds of people had been convicted based on SBS testimony from medical experts. Some of them were undoubtedly guilty. But if Plunkett was right, some of them almost certainly weren’t.

Naturally, defense attorneys began asking Plunkett to testify. He obliged. The same year his study was published, Plunkett testified in the trial of Lisa Stickney, a licensed day care worker in Oregon. She had been charged with murder for the death of a young boy in her care. According to Stickney, she was in another room when she heard a thud. She rushed over and found the boy on the floor near an overturned chair, with blood coming from his head. But according to prosecutors, an autopsy showed the boy had the symptoms that conventional wisdom held could only have come from violent shaking. Thanks in large part to Plunkett’s testimony, Stickney was acquitted.

The acquittal was another landmark moment in the SBS story. Plunkett was now a threat to SBS cases all over the country. The office of Deschutes County, Ore., District Attorney Michael Dugan responded with something unprecedented — it criminally charged an expert witness over testimony he had given in court. One of the state’s experts also filed an ethics complaint against Stickney’s other expert witness. The actual charges were filed by ssociate District Attorney Cliff Lu — four counts of “false swearing,” a misdemeanor charge related to perjury. Dugan’s office also contacted other prosecutors across the country to tell them that Plunkett was under criminal investigation. It was a pretty obvious effort to silence him — to prevent him from testifying in other cases. No defense attorney was about to call a witness if they jury would also learn that he was facing criminal charges over testimony he had given in court.

Because the charges stemmed from Plunkett’s testimony in an SBS case prosecuted by Dugan’s office, he and his assistants were eventually forced to withdraw from the case. The charges were then picked up by the office of the Oregon Attorney General. Perhaps this was just a reach by a rogue DA’s office. Perhaps once the state attorney general and his staff of professionals reviewed the case, they’d see the charges for the farce that they were. Nope. Oregon assistant Attorney General Eric Wasmann took up the case and brought Plunkett to trial.

I’ve been covering the forensics and the criminal justice system for 12 years. There have been some really bad expert witnesses to take the stand in U.S. courts. More than a few of them have been the main reason why an innocent person went to prison — and even to death row. I can only think of a couple of instances in which the expert was criminally prosecuted, and those cases were only after overwhelming evidence of really egregious misconduct, such as faking test results. The charges against Plunkett were about inconsequential details for which the worst possible explanation was simply that Plunkett had misremembered. Half the charges were dropped before trial. A judge acquitted him on the other two.

One of the remaining charges involved another expert witness named Mary Case. She was an ardent supporter of the SBS diagnosis. Plunkett was asked in court if he had ever participated in another trial in which Case was involved. He replied that to his knowledge he hadn’t. It turns out he had. But this was a man who testified in court many, many times. He had often been asked about Case’s work, even if she wasn’t testifying for the other side.  That’s an incredibly petty inaccuracy on which to pursue criminal charges. Plunkett had little to gain by deliberately giving a false answer to that question. Even Case herself — who again, believed Plunkett was wrong about SBS — told the ABA Journal in 2005, “I felt it was kind of a petty charge and I didn’t want to be involved . . .  his liberty or his livelihood could be lost for saying something slightly incorrect.” Asked why an expert witness like Plunkett could be facing criminal charges, Case responded that he must have “angered the prosecutor.”

Today, the scientific consensus on SBS has since shifted significantly in Plunkett’s direction. In 2015, the Post asked biomechanical engineer Chris Van Ee to measure the acceleration to the head produced by shaking versus that of a short-distance fall. Van Ee’s experiments found that the falls produced orders of magnitude more acceleration. Other researchers have found that other conditions ranging from bacterial infections to genetic conditions can produce symptoms to those commonly associated with SBS. Even the man who helped introduced the theory behind SBS now says the science is in doubt and has called for a review of SBS cases.

According to the National Registry of Exonerations, 16 SBS convictions have been overturned. Plunkett’s obituary puts the figure at 300, and claims that he participated in 50 of those cases. I’m not sure of the source for that figure, and it’s the first I’ve seen of it. But whatever the number, Plunkett deserves credit for being among the first to sound the alarm about wrongful SBS convictions. His study was the first step toward those exonerations.

Someone like Plunkett may not be the first person to come to mind when we think about whistleblowers, but that’s exactly what he was. I doubt he could have anticipated the unhinged reaction to his study and testimony — who could? But even after the criminal case and attacks on his credibility, he continued to speak out about SBS, and he continued to testify. In addition to the criminal charges, he also had to beat back ethics complaints, as have other SBS skeptics in both the United States and Europe. He certainly didn’t get rich from his heresy — one defense attorney interviewed by the ABA Journal pointed out that Plunkett often didn’t charge for his testimony.

Plunkett has bascially been vindicated in the years since his trial. What about the people who went after him? According to his LinkedIn profile, Eric Wassman is now a circuit court judge pro tem. As of February, Cliff Lu was still an assistant district attorney in Deschutes County. Former DA Michael Dugan was soundly defeated in 2010 after 23 years in office, and amid allegations of sexual discrimination and possible wrongful convictions. Dugan appears to have since joined the Malheur County, Ore., DA’s office as an assistant district attorney, where in 2014 he was pursuing a racketeering case against two men for selling medical marijuana. In 2015, Deschutes County endured another forensics scandal — county officials revealed that as many as 1,500 drug cases may have been tainted by a corrupt crime lab analyst.

John Plunkett died last week after a long battle with cancer. He was 70 years old. He ought to be remembered alongside people like John Edland, Michael Bowers and Mary and Peter Bush, and Emily Ward — people who tried to sound the alarm about dubious forensics, and were attacked and pilloried for doing so.

And among the wrongly accused whom Plunkett’s advocacy helped to free, I can only imagine that he’ll be remembered as a hero.