A 6-year-old boy was found dead yesterday morning, his hands and ankles bound and a gag stuffed in his mouth, in a water-filled bathtub in his Southeast Washington apartment, authorities said.

The boy appeared to have been dead for hours, perhaps longer, police said. He was alone in the apartment when his grandmother found him at 8:15 a.m., facedown in about a foot and a half of water, they said. The grandmother, who had come by to pick him up for summer camp, called 911 and was "hysterical" when police and rescue workers arrived, authorities said.

Police identified the child as Don Miguel Wilson and said he lived in the apartment with his mother, Julia Barber, and his 11-month-old brother. Investigators were questioning the mother last night, and the 11-month-old was in the care of the city's child welfare agency.

Police said that the cause of the boy's death has not been determined and that they had no suspect or motive.

The grandmother, Juanita Barber, told police that the front door of the apartment was unlocked, which she said was unusual. When she found Don Miguel, his ankles were bound, his hands were tied behind his back and some kind of gag was in his mouth, police said. He was wearing play clothes, they said.

Relatives and others described Don Miguel as an energetic, affectionate, high-spirited youngster who enjoyed sports, electronic toys and helping work on a relative's car.

"This is beyond tragic. It's something that should anger anyone, that a youngster could be so sadistically killed," D.C. Police Chief Charles H. Ramsey said.

Police were attempting to determine why the boy was alone and for how long. They said Julia Barber was with Don Miguel's brother and came to the scene after being contacted by the grandmother. Police provided no other details about the mother's whereabouts. One relative said Julia Barber is a nursing assistant.

Don Miguel was pronounced dead in the second-story bathroom of the brick apartment building he'd lived in for most of his life. For hours, the crime scene investigators had to work around his body. Medical examiners finally removed the body late in the afternoon.

The medical examiner's office is conducting an autopsy to determine time and cause of death. Investigators said the stages of rigor mortis might have been hastened by the water, making it difficult to quickly establish a time of death, Ramsey said.

Some of the victim's relatives gathered at the police department's violent crimes branch, where detectives were questioning the mother and others in hopes of uncovering leads.

Brazil Smith, the boy's maternal great-grandfather, often cared for the child during the day.

He said that Don Miguel and his younger brother were very close.

When he dropped Don Miguel at his mother's house each night, Smith said, the younger brother would bypass Smith and go right to Don Miguel. "Don was crazy about his little brother, and his little brother was crazy about him."

He remembered the youngster as a "vibrant, all-American boy," and he also praised the boy's mother, whom he described as an "outstanding parent." She was always doing things for her children, Smith said.

A great-aunt, Patricia Smith, recounted how Don Miguel would fearlessly approach her mastiff and how he would jump around with a towel wrapped about him, imitating Superman.

At his home in Southeast Washington, Donmiguel Wilson Sr., the boy's father, was accepting condolences and trying to fathom what happened. He said he had separated from Barber about two years ago. He saw his son regularly, he said, and they last got together on July 4.

"I'm still kind of blurry up top," Wilson said. "It's hard to believe. Somebody killed my son. Somebody murdered my child."

Wilson said young Don Miguel "would just run to me and hug me tight. . . . I can see him running up the street right now."

The boy was to begin the second grade in September at M.C. Terrell Elementary School, just down the street from his apartment in the 3200 block of Wheeler Road. Neighbors and others who knew him said Don Miguel liked to play football, basketball and video games and often tore around the courtyard on his bicycle.

They said he was polite and friendly at home and at school, recalling how generous he was with his hugs.

"Don Miguel was a nice child, very loving," said Anitha Davis, an administrative assistant at Terrell. "He would always give me a hug before he left for home."

"I really don't know what to make of this," said Andrew Haltiwanger, who lives in the apartment complex. "He was just a happy little boy, and they seemed like a happy family."

Other residents said the area, known as Congress Heights, has long been known as a dumping ground for stolen cars. There have been some drug problems and occasional violence, they said, but nothing to match yesterday.

"Even with all the crime we see in the District, you don't really see children targeted like this," said community activist Sandra Seegars.

Don Miguel was the sixth juvenile slain this year in the District, the 30th since January 2004, a spate of violence that has outraged city officials. The most recent previous casualty was Donte Manning, 9, who was fatally shot in March while playing outside his apartment in Northwest Washington.

Ramsey noted that Donte appeared to be hit by random gunfire, adding, "Unlike Donte Manning, this clearly was intentional."

Capt. C.V. Morris, head of the violent crimes branch, said eight or nine detectives are working the case.

Staff writers Henri E. Cauvin, Allan Lengel and Martin Weil and staff researcher Bobbye Pratt contributed to this report.

Don Miguel Wilson, shown here with his baby brother, was discovered in the tub. Donmiguel Wilson Sr., the slain boy's father, and Acquasia Wilson, the boy's half sister, also live in Southeast Washington. "It's hard to believe," said Wilson, who said he saw his son regularly. "Somebody murdered my child."