WASHINGTON — Margaret Dickinson first met Brian Slaughter nearly 30 years ago, in the forgotten world that was Forest Haven. She was a graduate student, about to start work at the District of Columbia's facility for the mentally retarded. He was a resident, a young man who had lived there since age 10.

As Dickinson took in the conditions that day — the toilet overflowing into the day room, the two attendants engrossed in TV, the 60 idle men — she wondered how she could ever work at such a place. Shaking her head, she half-sang a line from an old hymn, "Nobody knows the trouble I've seen."

A deep voice sang back, "Nobody knows but Jesus."

It was one of the men sitting on the bench along the wall.

"He was holding his trousers with his left hand because he didn't have a belt," she said, "and he had three big safety pins in the place where the zipper was. Most of the day's menu was all over his T-shirt, and he had shoes with no shoelaces and no socks."

There was one more thing: He was blind.

"Hi, I'm Brian," he said, extending his hand. "And I'm a gospel singer."

Years later, with Dickinson's help, Slaughter has become exactly what he said he was: He is the gospel singer.

It is hard to reconcile that picture of Slaughter, now 56, with the life he leads today.

Wearing dark glasses and, often, a red fez, he presides over the keyboards at the Art and Drama Therapy Institute, a daycare program in Washington for adults with mental retardation.

Slaughter is the assistant music instructor, receiving $7 an hour. He also stars in the Inspirational Choir and Moroccan Ensemble, which appears at churches and special events several times a month and has a CD and video. Recently, he soloed at the 23rd Annual Pacific Conference of Disabilities at the Sheraton Waikiki in March, returning with a white Panama hat and a love of sushi.

"I like good gospel music," Slaughter said in his preacherlike voice. "It starts my day off right."

Slaughter never forgets a name. He has hundreds of gospel songs in his repertoire and can launch into "Peace, Be Still" or "Precious Lord, Take My Hand" with a natural ease and authority. But he cannot read or write, and he would not be able to find his way to the store. Often, he can't recall exactly when something happened. But he has lots of plans for the future.

" 'Gospel Time!' That would be a good show," he said.

Slaughter is one of the few success stories that emerged from the institutional shame of Forest Haven. For decades, the D.C. facility, in Laurel, Md., reflected an era when society's most vulnerable citizens were hidden away with inadequate programs or care. The facility closed in 1991, sending about 1,100 people to a new system of group homes that would in time also be cited for its failings. A federal lawsuit against the District continues to this day on behalf of the former residents.

But Slaughter had something to hold on to that most others did not: his dreams of music.

LONG AND WINDING ROAD

Brian Xavier Slaughter was born three days before Christmas 1950. He and his twin, who lived just a few days, were three months premature. His mother, 19, already had two young children and a disintegrating marriage.

Iris McConnell, now 75 and a retired federal government employee, said she still gets "very emotional" about that period, which she has written about in a manuscript she hopes to publish someday.

"Sometime during his first week at home, I was examining his body to see if he had all his parts when I realized I had him in the light of the bulb with no shade on it and there was no response to the light," she read aloud recently in her suburban home. "He never even squinted."

McConnell quickly learned there were few options for a special-needs child in the 1950s. At 7, Brian entered a program at an elementary school but was soon released because he could not function independently, McConnell said. As D.C. officials sought another place for him, she grew desperate.

"I had nowhere for him to go, nor could I afford anything, so every day I would close my young son in his room," she said. She worried he might hurt himself while left alone.

Finally, a D.C. official convinced her that her older children would be better off if Slaughter went to Forest Haven, McConnell said. She'd heard "nothing good" about it, but she was "tired." The 10-year-old would have to be made a ward of the court.

"We were (case) number 15 that day," McConnell recalled. "Brian was dressed in his shirt and his little bow tie, clean and totally oblivious to what was about to go on. And when they called his name and I went forth, and the judge said whatever he had to say and then he struck that gavel and said, 'Committed,' it was just like my heart just left my body. 'What did I just do?' was what I said to myself."

The boy was led away by a caseworker and entered institutional life. Details are sketchy about those years. There were home visits for holidays. By the time he met Dickinson, he had lived at Forest Haven more than half his life.

"Are you going to be our new chief?" he asked her that day.

"Yes, I'm going to be your new chief," she said she replied, "and I'm going to get you out of here."

A year and a half later, in 1981, Slaughter moved into a group home. He had small jobs stuffing envelopes, folding papers. He found his niche in 1992, when Dickinson and artist and therapist Sirkku Sky Hiltunen started the Art and Drama Therapy Institute.

A MAGIC PLACE

The two have created an environment that could not be more different than Forest Haven. It is a colorful, eclectic place, a magic land of artwork, costumes and musical instruments. Here, a shy, mentally disabled woman dons an ornate dress and hand-painted mask and stars in a Japanese fairy tale. A young man who wears a helmet because he falls so often sings his own spirited version of opera.

"I believe these people are heaven's ambassadors," Dickinson said. "They're highly evolved, special beings. They are our teachers."

The center has about 160 clients, 30 of them former residents of Forest Haven.

When Dickinson started the choir a few years ago, Slaughter quickly became the breakout star. He learned his songs, he said, listening to gospel radio. When he sat down at the keyboards, "the music just came out."

The two dozen members rehearse twice weekly. Clients must audition for the coveted spots and prove they can remain focused.

Everywhere they go, their raw energy and open-faced joy has crowds jumping to their feet. Once, Dexter Slaughter attended a Special Olympics ceremony and was surprised to see his little brother and company up on the stage, owning it. "I knew he could sing, but I didn't know he could turn out a room," Dexter said.

Recently, Iris McConnell was at a seniors event when she heard the voice of her youngest child speak into a microphone, "Testing ... testing ... "

Then the Inspirational Choir and Moroccan Ensemble launched into one of its favorite hymns, "O Happy Day."

For Brian Slaughter, gospel singer, it was another very happy day.