Does Sex 'Polygraph' Rule Out Child Abuse?

Oct. 16 -- Bruce McLaughlin was once known as a successful attorney, loving husband and dedicated father of four adoring children.

Now, his reaction to a strange test — a kind of penile sensor that's meant to be a kind of a sexual lie detector — may mean the difference between freedom and jail.

McLaughlin's problems began when he and wife, Robyn, broke up after 16 years of marriage. And things only got worse — Bruce McLaughlin ended up in prison on charges of sexually abusing three of his four children.

By the time ABCNEWS' Primetime met Bruce last November, he had already spent 4 ½ years behind bars for a crime he insists he didn't commit.

"I wouldn't wish this on anybody who has had to go through what I've gone through," he said.

Damning Testimony

One night, almost seven years ago, Bruce and Robyn McLaughlin had a fight at home.

Robyn said there had been domestic violence before but this particular night was "the last straw."

She complained of a twisted arm and was taken to the hospital. Bruce was arrested, charged with assault and barred from the family home. The charges were later dropped and Bruce claimed any physical abuse was mutual.

But Robyn filed for divorce and custody of the children immediately became an issue. Saying he wanted to be a better, more honest husband, Bruce wrote a letter to Robyn revealing he had cheated on her.

The confession of infidelity ended any chance of reconciliation. Then, almost two years after the couple separated, Bruce was arrested and charged with 26 counts of child sexual abuse.

From the very start, Bruce maintained he was wrongly accused. But there was dramatic, convincing testimony against him from his own children.

Bruce McLaughlin was convicted of child sexual abuse against three of his four children and sentenced to 13 years in prison.