The rape and murder happened in 1983. At the time, people thought we were a fairly advanced society. Horses had long since given way to cars. We had science. The law had gone through the Warren Court and come out better on the other side, protecting the rights of defendants in what today might be considered some social justice fashion. So a conviction for a rape and murder in 1985 had to be pretty reliable, because we were a caring, smart, advanced nation trying to do the right thing.

Yet, the conviction of then-18, now-55, year-old Robert DuBoise, by a unanimous jury beyond a reasonable doubt, got everything wrong. Every single thing wrong.

To prove their case, prosecutors presented testimony from a local dentist who concluded that an injury on Ms. Grams’s cheek was a bite mark, as well as testimony from a dental expert who said that Mr. DuBoise had inflicted the bite.

An expert at trial testified to the jury about this bite mark, about it proving DuBoise was the person who did this, about how this was science, and science said DuBoise was the rapist and killer. Not the expert, but science.

A jailhouse informant also testified that Mr. DuBoise had confessed to killing and raping Ms. Grams along with his brother and friend.

People talk. Everybody knows people talk, and evil rapists and killers talk too, especially to their brother criminals when they have nothing but empty time to fill, so they fill it with talking. Sure, the snitch had a motive to make it up, but why would he do that to DuBoise? He had nothing against DuBoise, no reason to pin a confession to a horrific crime on an innocent guy. Who would do such a thing?

In 1990, the evidence from the trial was destroyed as part of routine house cleaning. There isn’t enough room to keep it forever, and once convicted, appeals exhausted, finality achieved, there was no reason to hang on to evidence of a crime where guilt was a certainty. Until it wasn’t.

Earlier this month, however, a prosecutor in Hillsborough County, Fla., made a startling discovery: The county medical examiner’s office had preserved rape kit samples in the case that were not used in Mr. DuBoise’s trial.

DNA testing of the samples confirmed what Mr. DuBoise had long said: that he was not responsible for the rape and murder of the woman, Barbara Grams, 19, prosecutors said.

In 1985, as advanced as we believed we were in our empathy and science, DNA evidence had yet to become a thing. Even if it had, there are serious questions whether anyone would have bothered, given the time and expense it required when it did become a thing, and given the strength of the evidence against DuBoise, making it superfluous since we already knew he was certainly guilty.

But in 2020, the miracle of science has continued to advance just enough to know a few more things, even though we were so damn smart in 1985, so very advanced in our knowledge, that few would have believed this is where we would be now.

We know bite mark evidence is garbage. Ironically, a review of the bite mark evidence in this case revealed it wasn’t even a bite mark, making it error atop garbage.

We knew that jailhouse rats are the worst, least reliable, source of “confessions” because they have an overwhelming incentive to fabricate confessions by anybody they get close to in the slammer. They make it up. They lie, and they lie all the time.

And then there’s the DNA, which is of limited worth to prove guilt, since the certainty of its source is nowhere as clear as the 20-million-to-one crowd would like it to appear, and it travels all over the place, particularly when not well handled. Back in 1985, the proper handling of DNA was not a concern to anyone, both because we didn’t know or care about DNA at the time and we were still light years away from appreciating how DNA from one source could end up somewhere else.

But DNA is extremely good at excluding a person as the perpetrator of a crime.

Mr. Warren said he had apologized to Mr. DuBoise “on behalf of the entire criminal justice system.”

“The only person who benefits from wrongful conviction is the actual perpetrator,” Mr. Warren said. “Wrongful convictions tear at the very foundation of our system and everything that prosecutors stand for: public safety, fairness and justice. Knowing that such an egregious mistake could happen here is gut-wrenching.”

This wasn’t a case where a cop lied or fabricated evidence to convict an innocent man. The prosecutors had no inkling that the wrong guy was sitting in the defendant’s chair. There was no malice toward DuBoise, but a sincere belief that they were prosecuting a terrible person, a rapist. A killer. A man who deserved to spend the rest of his life in prison, if he deserved to have a “rest of his life” at all.

But these stupid, misguided, clearly wrong beliefs about the value of science, the efficacy of forensic techniques like bite-mark analysis, the persuasiveness of a jail-house informant coming forward with a jail-mate’s confession, the magnificent good fortune of a rape kit with DNA to be discovered and tested to learn that the man in prison these many years was innocent all along, happened in the dark ages, 1985.

We could never get it wrong if this case arose today, because today our science is so much better, our understanding of the weakness of testimonial evidence so much more advanced, our refusal to accept voodoo like bite marks just because some cabal of forensic experts for hire say it’s legit. Sure, we thought we knew it all back in 1985 because we were so very smart, so very advanced, so filled with our passion for justice, but we were so very wrong.

Surely, no poor, innocent defendant will ever be convicted again, like poor Robert DuBoise was in 1985. Today we know better, because we are so very smart, so very advanced, so filled with our passion for justice, that we would never be as wrong as we were in 1985.