He was 15, his relatives said, not old enough for a driver's license. He had yet to even shave. But he was eager to work -- to buy a Ford Mustang, bright yellow, and a big house with a pool for his family. And when he got his next paycheck, he told his younger cousins, they would have a pizza party and go to the fair around the corner from his Wheaton home.

Instead, three weeks after he found work, Michael Francisco Barrios is a case file at the Maryland medical examiner's office, a victim of a freak accident Tuesday in North Potomac. During a landscaping job, authorities said, he fell into the grinding machinery of a mulch-spreading truck. A co-worker found his remains a short while later.

Barrios's death, in a neighborhood of three-car garages and immaculate lawns, is under investigation by the Maryland Occupational Safety and Health Administration and by the branch of the U.S. Labor Department that deals with child-labor laws. The youth worked for TopMulch, a company with about 20 employees based in the Montgomery community of Brookeville, owner Paul Saiz said.

"It's hard, and we feel bad for the family," Saiz said yesterday. But he contradicted Barrios's relatives, saying that paperwork provided by Barrios showed "he's not 15 -- he's 17." Saiz said he has photocopies of Barrios's identification and work permits.

"That would be something the investigation will look into," said Linda Sherman, spokeswoman for the Maryland Department of Labor Licensing and Regulation. "This investigation is, number one, serious, and it's thorough. We're looking at many, many areas here. And again, this isn't about blame. It's about safety."

Barrios, a U.S. citizen, was born in Los Angeles but grew up in his mother's native Guatemala after she took him there as a baby. He returned to the United States in December, said an uncle, Luis Villeda. His mother had been living here for years, working as a nanny in Montgomery County.

The family moved into the basement of another uncle's brick bungalow in Wheaton, near Thomas Edison High School of Technology, where his mother had hoped to enroll him, said an aunt, Marisol Villeda. But she said his mother could not produce paperwork necessary to get him into school. So he stayed home and cared for his 10-year-old sister, Angie.

"He got bored in here," Marisol Villeda said, adding that Barrios would say, " 'I don't want to stay here anymore. . . . I'm depressed.' "

So he latched onto the idea of a job. For weeks, Marisol Villeda said, Barrios kept telling his mother: "You don't need to work anymore. You've worked for 15 years. I want to help."

Luis Villeda would challenge him, hoping to focus his nephew on school instead of labor. "I said, 'How are you going to work? You're a little boy.' He said, 'Watch, watch.' "

Three weeks ago, Barrios's grandmother took Angie back to Guatemala, because she was unhappy and bored. So Barrios was free to leave the house and work, and he got a job with TopMulch.

A cousin, Katterinee Villeda, 13, stood on the front stoop of the Wheaton bungalow yesterday, wearing a Mickey Mouse T-shirt and recalling that Barrios seemed lonely the final time she saw him. He tried to talk her out of going to bed. "The last night he was alive, he was like: 'Stay with me. Just one more hour.' "

He was homesick for Guatemala, and although Katterinee usually went to bed before 9 p.m., that night she stayed up until 10, talking about memories of their lives in Guatemala -- of the river and the rocks they tried to balance on until they fell in.

Barrios called Katterinee his "pretty muneca" -- his "pretty doll" -- and yesterday she shook her head, talking about eating Oreo ice cream sandwiches with him after she came home from school; about buying stink bombs and setting them off in their Uncle Luis's car before he went on a date; about Barrios sitting on the couch in the upstairs living room, drawing the dream home in Guatemala that he hoped to someday own.

"When we get to Guatemala," he would tell Katterinee, pointing out different parts of the house, "we'll be in the pool with my sister, and you can teach me to swim."