DENVER — A young man who killed four people at a church and a missionary training center had attention deficit hyperactivity disorder and harbored bitterness for being an outcast, his parents said in their first extended comments.

Matthew Murray, however, gave no indication he was about to explode in violence, they said in an interview to be broadcast today and Friday on James Dobson's "Focus on the Family" radio program.

Although Ronald and Loretta Murray have issued statements to the media, the devoutly Christian couple gave Dobson their first public impressions of what led their 24-year-old son to go on his rampage in December.

"Focus on the Family" provided an advance copy of the broadcast to The Associated Press. On the program, the Murrays met David and Marie Works, the parents of two sisters who their son had killed. The Workses forgave the Murrays.

Murray killed two people at a Youth With a Mission training center in suburban Denver, slept in his own bed at his parents' house that night, then drove 60 miles to Colorado Springs, where he killed the two sisters.

An autopsy concluded that he shot and killed himself.

In a portion of the interview cut from the radio show because of time constraints, Loretta Murray said her son called a cousin in Utah shortly before the training center shooting, "pouring out his heart" about how depressed and lonely he was.

According to interviews and Murray's own Internet postings, Matthew Murray was a disturbed young man in search of belonging. He dabbled in the occult, briefly joined the LDS Church and turned against charismatic Christianity.

The Murrays said their son had problems communicating and writing because of his ADHD, was brilliant at computers, and felt rejected and marginalized, unable to forgive his perceived tormentors.

"The lesson is that unforgiveness leads to this bitterness and then opens you up to the spirit of Satan, to the spirit of whatever, and when that occurs, it becomes a power that people cannot control," said Ronald Murray, a neurologist.

Murray said that his son "had never expressed a desire for violence toward anybody," and that neither he nor Matthew's mother knew he owned weapons.

"He was told he was loved every day," Ronald Murray said.

In a statement to the AP, a Murray family spokeswoman Casey Nikoloric said Matthew was diagnosed with ADHD between ages 4 and 5 and began taking Ritalin at 5.

At 19, he decided to "stop all medications due to side effects" such as weight loss, drowsiness and grinding his teeth at night, and as far as his parents knew Matthew wasn't taking medication at the time of the shooting, the statement said.

Prescribing drugs such as Ritalin to treat ADHD, especially in young children, is controversial.

A year ago, the Food and Drug Administration asked ADHD drug manufacturers to develop guidelines to alert patients to "possible cardiovascular risks and risks of adverse psychiatric symptoms associated with the medicines."

Russell Barkley, a South Carolina psychologist who specializes in ADHD research, said the drugs, if taken regularly, reduce aggression and anti-social behavior.

Barkley said one study he conducted showed that 22 percent of people found as children to have ADHD had carried out an assault with a weapon by the time they reached adulthood.

"It's a sad situation, but I doubt that ADHD alone was the sole contributing factor to the violence," Barkley said, adding that other factors, such as low self-esteem and victimization, can contribute to outbursts.

Matthew Murray attended school for kindergarten and first grade but could not focus or pay attention, so the family decided to school him at home, Loretta Murray said.

Internet postings believed to have been written by Matthew rage against the strict biblical curriculum his parents used. But Loretta Murray said Matthew chose each year to continue home schooling.

In the statement to the AP, the Murrays' spokeswoman said Matthew wanted to be homeschooled, passing on the chance to attend "regular school," and talked just a few months ago about enjoying homeschool.

The night before the shootings, Matthew told his parents he was going out with friends for his birthday. The cousin called Loretta Murray just before midnight to tell her about Matthew's emotional state. She asked her husband to call him.

When Ronald Murray reached his son's cell phone at 1:15 a.m., Matthew said he was eating at a restaurant with friends and was coming home. He had just shot and killed two people at the Youth With a Mission center in Arvada.

The next morning, Matthew appeared fine, and his mother told him to be careful driving in the snow. Later, Matthew went to the New Life Church parking lot and fatally shot sisters Stephanie, 18, and Rachel, 16, and wounded their father.

In the Focus on the Family interview, Stephanie's twin sister, Laurie, told the Murrays that as she cowered in the family's van, she forgave the shooter.

"Your loss is more than mine," she told the Murrays.

Her father, David Works, said forgiveness was simply part of the Christian walk.

"Without forgiveness," Ronald Murray said, "I don't think we could have moved on."