Something looked wrong as Mark Dunn walked over to his wife that May afternoon.

He had just returned from work and saw her lying on the couch, the only place in their Apple Valley home where she found comfort from the chronic pain that plagued her for a decade.

"She looked too still," he said. "I touched her and I knew she was gone."

Eight years later, the details of how Doreen Dunn died are being examined in a Dakota County courtroom. Months before her death, Dunn became a member of the right-to-die group Final Exit Network, Inc. The organization faces charges of assisting her suicide and interfering with a death scene.

As the jury trial opened Monday, Robert Rivas, the attorney for Final Exit Network, and Dakota County prosecutors clashed over what qualifies as "assisting" a suicide.

Final Exit Network, a Georgia-based nonprofit, provides information and support to people across the country who are terminally ill or in chronic pain and want to kill themselves. Attempts in other states to convict members of the organization with assisting a suicide have failed.

Former Final Exit Network President Thomas Goodwin, the state's first witness, told the jury that members of the organization understand they walk a fine line legally.

The group must navigate a patchwork of laws that vary from state to state, and their goal has been "to push the envelope but stay in the law as we knew it," Goodwin said.

Dunn, 57, contacted the nonprofit in January 2007, without telling her family. She told the organization that for 10 years she had lived with "unbearable excruciating" pain that she could not escape.

Dunn, a mother of two, was once a musician who trained in Bordeaux, France, Mark Dunn told the jury Monday. But she was transformed by the pain that started after a medical procedure. Light and sound — even music — pained her.

Her son, Jesse, and husband, Mark, said Monday that she had been depressed for a long time before she contacted the Final Exit Network. Mark Dunn was in the process of moving out, and his boxes lay around the house on the day she died.

Mark said he knew his wife supported assisted suicide. But neither he nor Jesse knew she planned to commit suicide.

'Exit guides'

Dunn killed herself in her home by helium asphyxiation. That method of suicide is recommended by the Final Exit Network. It is particularly difficult for law enforcement to detect, Prosecutor Elizabeth Swank said.

Two members of Final Exit Network visited Dunn on the day she died, Swank said, and removed evidence of the suicide.

"Exit guides" from the organization sometimes hold someone's hands as they die, then the guides remove the helium tanks and plastic bag, Goodwin said. He added that many people do not want to be remembered as having committed suicide.

"There was a desire for privacy and to go gently and to be remembered for who you were," he said.

The medical examiner initially ruled that Dunn died of natural causes.

Two years later, a Georgia investigation of the Final Exit Network unearthed documents showing Dunn became a member of the group, one of the steps required to enlist the organization's help.

In 2012, Dakota County Attorney James Backstrom charged four people and the Final Exit Network corporation in connection with Dunn's death. But Monday the state was prosecuting only the organization, which faces a maximum of $33,000 in fines.

Rivas said prosecutors will talk about how Dunn died, but he urged the jury to watch for proof that members of Final Exit Network assisted the suicide.

"That moment will never arrive," Rivas said.

As for the four members of Final Exit who were also charged, one defendant has since died and another is too sick to stand trial. Dakota County District Judge Karen Asphaug dismissed the charges against a third. The fourth, Lawrence Egbert, who was the group's medical director, will be called on by the state to testify against the Final Exit Network during this trial.

The trial is the latest chapter in a long court saga.

The Minnesota Supreme Court previously ruled that the state law prohibiting "advising" or "encouraging" suicide violated citizens' free speech rights. But the Final Exit Network could still be prosecuted for directly assisting in Dunn's suicide, which could include physical help or the use of speech. The state Supreme Court declined to hear prosecutors' appeal, sending the case back to trial court.

Staff writer Stephen Montemayor contributed to this report.