Carol Waltman remembers the moment when a photograph of Dennis Dechaine brought her 10th high school reunion to a standstill.

It was early July 1988. Waltman was among the group of about 100 people celebrating at the Wonder Bar, a pub in Madawaska, a mill town on Maine’s northern border.

Waltman and many of the others at the reunion had grown up with Dechaine, who was a few years older.

The party went silent when his face came on the big-screen television. Dechaine was accused of the kidnapping and murder of a 12-year-old girl.

Waltman was stunned. She knew Dechaine as well as she knew her own brothers. How could this gentle person, known sometimes by the nickname “Mouse,” possibly be involved in such a horrific crime?

“It was like, ‘Oh my God, of all people, Dennis Dechaine?”‘ Waltman recalled. “Dennis was a nice kid, a good kid, everybody was his friend.”

That moment was the genesis of a group called Trial and Error, made up of people who believe Dechaine did not kill Sarah Cherry and that he deserves a new trial or outright exoneration. Supporters have come and gone, but under Waltman’s leadership, the group has remained intact for 21 years.

Waltman organized the first meeting of Trial and Error in May 1989, about a month after a jury convicted Dechaine. There are now eight chapters statewide, some of which meet monthly.

A core group of about 30 supporters, known as “Team D,” are the most active participants. Beyond that, the number of supporters is hard to determine. There is no formal membership process except for the six-member board of directors, which includes Waltman, Dechaine and one of his three brothers, Don. About 2,500 people worldwide subscribe to Trial and Error’s electronic news updates, Waltman said.

Dechaine’s supporters have lobbied legislators, organized marches and commissioned a public opinion poll. They were influential backers behind a 2006 change in state law that lowered the burden for convicts seeking new trials based on DNA evidence.

And they have raised more than $200,000 in support of Dechaine’s ongoing effort to get a new trial. Funds raised by Trial and Error have paid for the work of private investigators, for DNA testing conducted at the request of Dechaine’s lawyers, for production and distribution of videotapes and books about the case, and other expenses.

Dechaine’s lawyers have been court-appointed and paid by the state. The Innocence Project, a nonprofit organization based in New York, also has funded some work by its own lawyers on the Dechaine case.

Many of the Trial and Error supporters came on board after the 2002 publication of “Human Sacrifice,” by Brunswick resident James P. Moore. The book asserted that Dechaine was innocent and that state officials botched the investigation.

William Bunting of Whitefield read the book and was so disturbed that he could not sleep for a few nights. Bunting got involved in Trial and Error, and has become one of Dechaine’s top supporters. He has visited Dechaine in prison about once every two weeks since the summer of 2003.

“Leaving Dennis sitting at the table behind that heavy slamming door never gets any easier,” Bunting said.

“For Trial and Error, this case has always been about the evidence,” he said. “I cannot understand how so many Mainers in positions of power and influence can ignore the overwhelming evidence that Dennis Dechaine is innocent, and that our criminal justice system has screwed up so badly, and does not care enough or is too blinded to seek justice in this case.”

At times, Trial and Error has come under fire for insensitivity to Sarah Cherry’s family.

During a court proceeding in Rockland in 1992, supporters wearing T-shirts emblazoned with “Trial and Error” stood and applauded when bailiffs escorted Dechaine into the courtroom.

In 2005, Trial and Error board member Morrison Bonpasse visited the homes and workplaces of some of Sarah Cherry’s relatives with the goal of convincing them that a new trial was justified. Cherry’s family told Bonpasse to stop bothering them.

Waltman said Bonpasse acted on his own. She apologized to the Cherry family, and told Bonpasse he was no longer welcome in the Trial and Error leadership.

Peg Cherry, Sarah Cherry’s grandmother, said the family has not had any further intrusions from the group.

Trial and Error is registered as a nonprofit advocacy organization without any paid staffers. It received about $9,000 in donations in 2008. Waltman, who works full-time at the Marden’s store in Madawaska, has volunteered her time as president.

Waltman said Dechaine, in many respects, reminds her of her husband, who also grew up in Madawaska and was close friends with Dechaine.

“If this would have happened to my husband,” Waltman said, “I think maybe Dennis would have done what I am doing because that is the kind of person he is.”