Father, Son Vanished at Favorite Hiking Spot : Tragedy: Exploring the park was a frequent pastime for the pair believed to have been killed by flash flood. The boy’s tennis shoe is found under seven feet of mud.

It is rugged and ripe for adventure--a perfect place for a father and son to explore. John Henderson and his boy, Matthew, returned to the zigzagging trails often.

It was the spot in Sierra Madre from which they disappeared after apparently being swept to their deaths Sunday afternoon by a flash flood.

On Monday, searchers found Matthew’s sneaker in the Bailey Canyon Park catch basin under seven feet of muddy water and muck.

Relatives said it was easy to identify because the child had adored his new shoes--they were the kind with the flashing lights in the heels, and for days he had stomped through the house, making them light up.

They had been a gift from his father, who doted on him, the boy’s aunt said.

“Nobody could come between him and his son,” said Laura Henderson, John’s younger sister, as she stood red-eyed on a bluff overlooking the ocean of mud that had collected in the debris basin in Bailey Canyon Park. “Matt was his life.”

As the search for John Henderson, 33, and his son, Matthew, 9, dragged into its third day, authorities held out little hope that they would be found alive. The two had been trekking through Bailey Canyon when a wall of mud and water roared down upon them.

Authorities suspect that a cloudburst deep in the Angeles National Forest was the reason for the sudden tragedy. Los Angeles County Sheriff’s Sgt. Pete Fosselman said no heavy rain had fallen in Bailey Canyon that afternoon, and the only sign the Hendersons and the other hikers had was the sudden rumbling that split the air as the torrent of water ripped through the canyon, uprooting trees, unearthing boulders and smashing a small bridge.

Sierra Madre city officials said park gates are closed in case of any danger, usually after warnings about brush fires. But the gates were open Sunday because there was no warning of rainfall or flash floods.

“There was not a high threat level,” Fosselman said.

Fellow hikers said the father and son were last seen chugging up a slope toward a waterfall.

“We saw them walking in the basin, then they turned up the canyon. . . . It gets really narrow up in the canyon, and there’s no way to get out,” said Terry Bing, 60, who was walking with her husband, Colin, along the trails in Bailey Park about 5 p.m. when the flood occurred.

“If it hadn’t started (drizzling), we would have kept meandering up the canyon just like them,” she said.

Most of the several dozen hikers in the canyon managed to scramble to safety, authorities said, but when everyone had left, rescuers noticed a lone car in an empty parking lot that was traced to Henderson. The Hendersons were farther up the canyon than anyone else, witnesses said, up in the area that was narrower and steeper.

A self-employed paralegal, Henderson worked out of his home so he could spend more time with his son, his sister said. Matthew, she explained, was the only child of a marriage that ended in divorce when the child was 1 year old. The family, she added, does not know where Matthew’s mother lives, and the father had raised his son since infancy.

The child, she said, divided his time between his father’s apartment in Sierra Madre, where they lived for about two years, and his grandparents’ home in nearby Arcadia.

But Henderson’s aunt, Mary Dunbar of Santa Barbara, said the father was Matthew’s predominant caretaker.

“That’s probably what he did the very best in his whole life--to be a father to his little boy,” she said.

Henderson’s sister added that the father regularly attended parent-teacher conferences at the parochial school Matthew attended, and encouraged his son in the child’s favorite hobby--karate. Matthew, relatives said, had doubled up recently on his lessons at the Red Dragon Karate Studio in Monrovia, hoping to earn a blue belt like his uncle George.

Matthew, a third-grader at Bethany Christian, was an excellent student, according to Principal Helen Cadloni. The Hendersons were regulars at school functions, and she characterized John Henderson as a very supportive father.

“It’s nice to think back on Matthew,” Cadloni said. “He was a nice boy, on the quiet side. I very rarely saw him at all, as far as disciplinary things went.”

John Henderson’s favorite pastime, Laura Henderson said, was exploring the mountains with his son.

Henderson, she said, was an experienced hiker and mountain biker who loved the trails that crisscross Bailey Canyon, whether he was exploring them on his mountain bike or taking them in at a slower pace with his little boy.

And that, she said, was the afternoon they had planned on Sunday when they disappeared.

Fosselman said the flash flood would have taken even the most experienced naturalist by surprise.

“Nothing they could have done could have prepared them for something like this,” the sheriff’s sergeant said.