Life got so overwhelming for Jillian Meredith McCabe that she threw her autistic son, six, off a bridge while on a walk with him. After that, the 34-year-old called the police and told them what she had done, NBC news reported.
Relatives told the American television channel that the mother had massive challenges in life, and had, in the process, suffered a mental collapse.
She had to take care of her non-verbal, autistic son, and her husband had a brain injury. She also had to deal with the death of her father.
"Jillian really struggled with her mental health and I know she was just out of her mind when this happened," said Ms Tanya McCabe, London's great-aunt, who had led the family effort to seek psychiatric treatment for her.
The mother was discharged more than once from inpatient care, the great-aunt said.
In the past, McCabe, who lived in the US state of Oregon, had spoken and written of "pulling a Thelma and Louise" - a reference to the movie in which two women drive their car off a cliff - as a response to the stresses of her life.
"We're all devastated," Mr Andrew McCabe, London's uncle, told NBC News. "London was a good kid. He loved hats. And his dad."
Said Ms Tanya McCabe: "It was terrible what we went through to get her the help she did get. We worked full-time to get her the services, but obviously, they weren't sufficient."
She said London's mother had expressed thoughts of harming herself, but the family did not imagine she would kill her son. "Jillian was always so patient with him, and loving. She really had a lot of compassion for his condition.
"When he was screaming at the top of his lungs, which was the only way he could communicate, she didn't get upset at all." Ms Tanya McCabe said the mother would comfort him and that she was amazed at how patient she was.
"So this was shocking and heartbreaking."
Jillian McCabe was charged on Tuesday with aggravated murder and manslaughter, Reuters reported.
The US Coast Guard sent two boats and a helicopter to help search for London, but it was four hours later when his body was spotted in the water, about 1km from the bridge, said the police.