On a July night in 1988, about 100 friends were gathered at the Wunderbar in Madawaska, celebrating their 10th high school reunion.

The party was loud and boisterous until a familiar face flashed on a TV screen.

“It was Dennis,” remembered Carol Waltman in a 2003 interview. “That mug shot, that terrible mug shot. Everybody just said, ‘Oh, my God,’ and that was the end of the party.”

And it was the beginning of Trial and Error, the group that has fought for the last 27 years to exonerate Dennis Dechaine, the Bowdoinham farmer who is serving a life sentence for the murder of 12-year-old Sarah Cherry. With the group’s support, Dechaine has challenged his 1989 conviction in every legal jurisdiction available to him and every time he has lost.

With a ruling Tuesday against Dechaine by the Maine Supreme Judicial Court, it’s time for the Trial and Error party to end.

When you look at something long enough, you change it. And that’s what Trial and Error has done over these years.

More than 500 murders have been committed in Maine since Sarah Cherry disappeared, dozens investigated by the same detectives who made the case against Dechaine.

The same prosecutors and the same judge were involved in thousands of other cases. But only one keeps coming back year after year.

What’s different is not the evidence – it’s Trial and Error.

The light the group has shined has exposed flaws in the way evidence was collected back in the 1980s. They have uncovered sloppy techniques by detectives who scribbled notes instead of recording interviews. And they have stirred up unethical behavior by Dechaine’s first lawyer, George Carlton, who apparently went around telling his buddies that his client was guilty.

But, despite their claims, they have not exonerated Dechaine.

The Trial and Error arguments fall into three camps.

The first group are Dechaine’s family and friends, who insist that the gentle soul they called “Mouse” could not have done what he is accused of. The second are those who argue that DNA evidence proves his innocence, and the third follows the arcane theories of author James Moore, who says he can prove Dechaine is innocent.

None of these arguments has done anything but keep the movement going.

Not being “the type” doesn’t prove anything. I am convinced that no one really knows anyone else, especially when it comes to questions of sexual desire. We all get surprised at some point in our lives when we learn something about a friend, a relative, a spouse or even about ourselves. If Dechaine was harboring urges to rape and murder a child, we shouldn’t be shocked if he kept it secret.

Dechaine’s best arguments have involved DNA. Dechaine demanded DNA testing of evidence before the start of his trial, something a guilty defendant wouldn’t do. Years after his trial, one of the victim’s thumbnails was found to have her own blood and some DNA from an unknown male. The sample was too weak to identify any individual, but it excluded Dechaine.

But it’s not the proof that Dechaine’s backers claim. They can’t connect the DNA to the crime. There were plenty of chances for the fingernail to be contaminated over the years with someone else’s DNA, and no way to prove that the killer was its source. DNA is powerful evidence, but it’s not magic. It can only tell part of a story.

Moore’s theories are based on his interpretation of the state’s evidence.

He says someone else could have kidnapped Cherry, planted papers from Dechaine’s truck at the crime scene, murdered her in the woods and escaped unnoticed while swarms of police were in the area looking for her. Moore uses the medical examiner’s testimony to make his own time-of-death calculation, which he says clears Dechaine because Cherry would have still been alive when he was taken into custody.

It makes for an intriguing book (he wrote “Human Sacrifice” in 2002) but not much else.

Here’s what we know:

On the night of July 6, 1988, Dennis Dechaine walked out of the woods in rural Bowdoin. He told police that he had been fishing and lost his way

Eventually, Sarah Cherry was found stabbed to death with a small blade, tied up with rope matching a piece in Dechaine’s barn, gagged with a scarf that belonged to Dechaine and left in a site about 400 feet away from his truck.

His papers were found at the last place Sarah had been seen alive, and the penknife he kept on his keychain had vanished.

Circumstantial evidence? Sure. But a lot of it.

Dechaine is either guilty or the unluckiest guy on the planet. It’s time to leave this case alone, and let Sarah Cherry rest in peace.