MacDonald’s story was that drugged-out hippies entered the home (which was often unlocked), beat him up, and killed the other three (his wife was also pregnant) while muttering, “Acid is groovy” and “Kill the pigs.” On the headboard of MacDonald’s bed the word “PIG” was scrawled in blood.

Prosecutors decided it was all too far-fetched and that MacDonald was the real killer. MacDonald was duly convicted of one count of first-degree murder and two counts of second-degree murder. He is currently serving three consecutive life sentences in Wilmington, N.C.

I’m 25 and had never heard of the case until a year ago, when I read Janet Malcolm’s The Journalist and the Murderer. Her book, which originally ran as two long New Yorker articles in 1989, investigates the ethical issues at play in how journalist Joe McGinniss handled his relationship with MacDonald before publishing Fatal Vision, his own 1983 bestseller about the trial.

If you’re still following along, that’s two big, influential books relating to the MacDonald case, the second of which is a response to the first. Now we have a third: A Wilderness of Error, by documentary filmmaker Errol Morris, who reopens the 40-year-old case and argues that the trial was handled poorly, that key evidence was ignored, and that there is reasonable doubt as to MacDonald’s guilt.

It would be impossible, or at the very least irresponsible, to evaluate Morris’s book without considering those that came before it. The Journalist and the Murderer had a lasting effect on me as a reporter, and I believe all journalists ought to read it.

Malcolm’s book examines the reporter-subject relationship, which is a rocky one indeed. Those of us who respect our craft are careful about handling subjects. We know the rules about quoting, and fact checking, and talking to someone “on-record.” Even when you cover all your bases, however, there’s no guarantee that your subject will be happy with the story.

Once or twice, a person I’ve written about has been displeased with what I wrote, although they had no factual disputes. It happens to all journalists, and though it doesn’t really matter, as long as you’ve done your due diligence and proceeded fairly, you can’t help but care. You feel a need for them to agree that your story was fair and accurate.

Malcolm writes that the unhappy subject of a work of journalism, once it is published, “tends to pick himself up and walk away from the debacle, relegating his relationship with the journalist to the rubbish heap of love affairs that ended badly and are best pushed out of consciousness.” But no conscientious journalist wants a person with whom they spent a lot of time, a person who cooperated and shared personal details, to end up feeling the experience needs to go on the “rubbish heap.”

In the instance of Fatal Vision, MacDonald didn’t just roll over and push his interaction with McGinniss “out of consciousness.” He sued McGinniss from prison, for fraud, and won an out-of-court settlement of $325,000. To read Malcolm’s book is to understand why MacDonald won. His complaint was that McGinniss misled him during the reporting, feigned a belief in his innocence, and misrepresented what he would write in his book.

Malcolm gives many examples, but the most damning is a series of letters from McGinniss to MacDonald, in which the former wrote things like: “Total strangers can recognize within five minutes that you did not receive a fair trial… It’s all so fucking awful I can’t believe it yet … It’s a hell of a thing — spend the summer making a new friend and then the bastards come along and lock him up. But not for long, Jeffrey.”

As anyone in the media business knows, all bets are off once a subject agrees to cooperate on the record. They can’t expect to have any say over what you write. In this regard, it’s hard to argue that McGinniss broke any law. But if you read those letters and then read Fatal Vision, in that order, you’ll see terrible dishonesty in how McGinniss dealt with his subject. The content and tone of Fatal Vision makes it simply shocking that its author could have written those letters. As Malcolm writes: “For almost four years … [McGinniss] successfully hid the fact that in the book under preparation he was portraying MacDonald as a psychopathic killer.” (McGinniss later penned a lengthy response.)

Compared to McGinniss, Errol Morris has done a far more ethical job of rounding up the facts in this case. He makes his own opinion known from the outset: He believes MacDonald may be innocent, but can’t be sure. At the very least, he believes MacDonald did not get a fair trial. And yet Morris is careful, in recounting all the evidence, to include facts that contradict his own view. After reading his book, it’s difficult not to think it at least possible that MacDonald is innocent. And if his innocence is possible, he shouldn’t be in jail.

A Wilderness of Error isn’t just thorough, it is very stylish: The book, though long and dense, is organized in sensible chapters by event or piece of evidence. Throughout the text are precise maps, sketches, and clippings from newspaper articles.

Morris, in most of his arguments, comes off as a reasonable gadfly. On the key issue of a coffee table in MacDonald’s living room that was supposedly turned over during the struggle between MacDonald and the killers, Morris presents, as a journalist would, the pure facts of how the prosecution treated the table. In court, prosecutors argued that there was no way it could have landed flat on its top, legs up in the air. As a result, they claimed, MacDonald must have arranged it that way. (Later in the book, we learn that a different person tried this same experiment and had different results.)

But then Morris asks, fairly: “Couldn’t there be a multitude of other explanations for the position of the coffee table … Even if it couldn’t have possibly landed that way in a struggle, even if it had to be placed in that position, what did it ultimately show about MacDonald’s guilt or innocence?”

Morris is a filmmaker as well as a journalist, and so his flair for the dramatic is obvious and at times a bit corny. He doesn’t set out to present “just the facts, ma’am” but instead hops onto a soapbox at the close of many chapters, spouting off about the efficacy of narrative or the inherent flaw in crime-scene notes taken by officers that in many cases had already formed their own snap judgment of what had happened. He quotes Kafka and Shakespeare. He opines, “It is a comedy of errors. MacDonald was accused of having staged the crime scene, but could anyone be sure of the position of anything?”

It’s hard to ignore the sheer volume of compelling evidence Morris combs through, most of which confounds the idea that MacDonald is guilty. Only a month before the MacDonald murders, a neighbor, Janice Pendlyshok, had her house broken into. The intruders scattered some clothing around and scrawled, “Look in the closet” in lipstick on her mirror. (There was nothing there.) This certainly suggests that MacDonald’s intruder story is plausible. (Pendlyshok, by the way, is never mentioned in Fatal Vision; the breadth of Morris’s reporting is truly impressive and worthy of journalistic praise.)

Then there’s the mysterious role of another local woman, Helena Stoeckley. In a pre-polygraph interview, Stoeckley told police that she believed she had been present in MacDonald’s house at the time of the murders. Since the murders, she added, she had been having nightmares in which she saw the word “Pig” written in blood on the bed headboard and MacDonald holding an ice pick (the real-life murder weapon).

MacDonald claimed that he remembered seeing, standing over him, three men, plus one woman who stood by wearing a floppy hat and boots and holding a candle. Stoeckley confirmed that she often wore a floppy hat and boots. MacDonald remembered Stoeckley holding a candle, and police found melted wax at the scene that did not match any candles in the house. A used match was found in one of the daughter’s rooms.

Jimmy Britt, a deputy marshal who had driven Stoeckley to Raleigh to testify, came forward in 2005 and said on record that Stoeckley, just before testifying otherwise, had told him she was present in the home at the time of the murders.

But Stoeckley was a drug addict, and in the end her apparent connection to the events was ignored. Frustrating though that is, Morris again demonstrates his careful reluctance to shout “I’m right!” when he mentions the fact that Stoeckley had knowledge of a rocking horse no one else could have known about, then qualifies that this doesn’t prove she was in the house, though he wishes he could say it does.

Errol Morris has written the definitive book on this case, or at least on everything that has happened thus far. In only three days, on September 17, a Wilmington, N.C. court will hold a new hearing about MacDonald’s case. You can bet that Morris will be there, and so might Malcolm, though perhaps not McGinniss.

Whether Morris’s book will have any impact on MacDonald’s current situation remains to be seen. It might sound like a long shot, but Morris has an impressive track record of effecting real change in the justice system. His 1988 documentary The Thin Blue Line resulted in the freeing of Randall Adams, who had been wrongly convicted of murdering a police officer and was serving a life sentence, one year after the film’s release.