Just days before professional wrestling star Chris Benoit killed his wife, his son and himself, the couple argued over caring for their mentally disabled child, who suffered from a rare medical condition, a lawyer with World Wrestling Entertainment said Wednesday.

"As we went back to the time line of events, it became pretty obvious from several different sources that Nancy and Chris had tension in their relationship, " said the lawyer, Jerry McDevitt. "I don't know what they said to each other, but they were constantly struggling with the difficulties of raising a child who, from all indications, may well have had Fragile X Syndrome."

Fragile X Syndrome is the most common inherited form of mental impairment, affecting boys twice as often as girls, according to the Emory University School of Medicine's Department of Human Genetics. It can lead to autistic-like behavior, and there is no known cure.

Investigators think Benoit, 40, killed his wife Friday and his 7-year-old son Daniel Saturday. He placed Bibles next to their bodies, authorities say. Sometime Sunday he hanged himself using a weight-machine pulley. The bodies were found Monday at the Benoits' exclusive Fayette County home near Peachtree City.

McDevitt said Benoit's wife didn't want him to quit wrestling but wanted him to stay home more often. She had recently undergone surgery on her neck and was in pain, he said.

"It's very difficult to raise a child this way. There's a lot of guilt, " McDevitt said. "Chris was traveling on the road; she was trying to deal with the problems on her own."

Gail Heyman, who co-founded the Fragile X Association of Georgia, acknowledged that having a child diagnosed with the syndrome can put a strain on the family. But, she said, it's a matter of choice how a couple handles the challenge.

"You can either accept the differences and to be more tolerant of each other, or have it work against you, " said Heyman, 50, of Marietta. Benoit and his wife had told friends and their physician that they were worried about where to send Daniel to school. The boy had just finished kindergarten at First Baptist Church School in Peachtree City.

"When they moved into this new area [last summer] and the child has to be placed in a new district, I gathered the tension somewhat exacerbated, " McDevitt said.

The pastor of First Baptist, the Rev. Kenneth Brown, said Daniel was a well-liked student. "Our observations were of a caring, loving family, " he said.

Pam Winthrope, whose 12-year-old son has been diagnosed with the syndrome, said her late husband reached out to Benoit about five years ago to see whether he would help them start a support group in greater Vancouver, where she lives.

"My husband asked him whether he wanted to be a public face for Fragile X, " Winthrope said Wednesday night. "But he wanted to remain very, very private about it."

The two men then talked briefly about what it meant to be dads to a child with the syndrome, she said.

"It's easier for mothers to accept it because we carry the child for nine months and learn to love them, " she said. "Fathers have a problem with assumptions of what they can and cannot do. 'Can they play football with me?' "

Last messages

New details about the killings emerged Wednesday.

Daniel appeared to have been killed in a chokehold because he had internal neck injuries but no visible bruises, according to Scott Ballard, district attorney for Fayette County.

Nancy Benoit, 43, had bruises on her back and stomach, indicating her husband had his knee in her back as he pulled on a cord that was around her neck.

Benoit killed himself by wrapping a cord around his neck that was attached to a weight machine. He released the weights --- about 240 pounds --- to cause strangulation, Ballard said.

During the weekend, Benoit made groggy calls to co-workers and left text messages, according to the WWE.

On Saturday, he said he was delayed in catching his flight to an event in Beaumont, Texas, because of family health issues, the WWE said. In one call he said "I love you" to a co-worker, who called it "out of context, " the organization said.

In other calls, Benoit said his wife and son were sick with food poisoning and that they had gone to the hospital, WWE said.

On Sunday, Benoit sent text messages to friends from his cellphone and his wife's cellphone. The last text message was sent at 3:58 a.m. Sunday, according to WWE.

The WWE lawyer tried to get inside the mind of the wrestling star to explain why he would kill his child.

"The time gap between the death of Nancy and the time he was with this child, it doesn't take much to figure out what was going on in his mind, " McDevitt said. "The mother can't take care of [Daniel], he'd killed her. He was going to jail. There was nobody left to take care of this little boy."

McDevitt could not find any other explanation why Benoit would take Daniel's life. The boy adored his father and had his pictures in his room, McDevitt said.

Also Wednesday, Benoit's longtime physician, Dr. Phil Astin, said he had prescribed testosterone for the wrestler in the past but would not say what, if any, medications he prescribed the day of their meeting.

"He was in my office on Friday to stop by just to see my staff, " Astin, of Carrollton, said. "He certainly didn't show any signs of any distress or rage or anything."

Not a 'roid rage'

That the violence went on for an extended period indicates it was not a "roid rage" sparked by steroid use, according to WWE and others.

Toxicology results from Benoit's autopsy won't be available for weeks.

Benoit received drug deliveries from a Florida business that sold steroids, human growth hormone and testosterone, according to the Albany County, N.Y., district attorney's office, which is investigating the business, MedXLife.com.

"This gentleman may have had other significant mental health problems, " said Gary Yesalis, an epidemiologist at Penn State University. "The death of Benoit and his family wasn't spontaneous. I don't see steroids had much if anything to do with this."

At the gate and stacked stone wall at the family's 8-acre home, flowers, stuffed animals and wrestling figurines were left by fans.

And so were notes.

One was written by a child in pencil on lined notebook paper. "I will miss you, we will always love you, " it says. "I left you my [toy] wrestler. See you in heaven."

Staff writers Mike Morris, Kathy Jefcoats and Bill Hendricks, researchers Sharon Gaus and Nisa Asokan and The Associated Press contributed to this article.

WHAT IS FRAGILE X SYNDROME?

> Fragile X is a common inherited cause of mental disability.

> It is caused by a mutation of a gene on the X chromosome. DNA tests identify people with the disorder.

> Approximately 1 in 260 women is a carrier of the gene.

> An estimated 1 in 2,000 boys is impaired by Fragile X. Girls are affected at a much lower rate, and the effects are usually milder.

> Effects range from mild learning disabilities to severe mental impairment. Those affected may be hyperactive, hypersensitive to external stimuli and have short attention spans.

> There is no known cure, but drug therapies are available to increase attention span and decrease hyperactivity.

Source: Dolan DNA Learning Center