The mystery began a month ago, when police found a woman lying on a street in Langley Park. She had been hit by a car or fallen onto University Boulevard.

"It was a rainy, nasty night, and a witness said there was a car in the area and a woman lying in the street," said Cpl. Debbie Carlson, a spokeswoman for Prince George's County police. "The witness got a license plate, but it turned out not to be right. They didn't see the crash, only the woman."

The unconscious woman had no visible injuries, but a CAT scan showed that she had brain swelling, Carlson said. She had no identification, and when she awoke, she could not tell hospital workers who she was.

She was moved from Washington Adventist Hospital in Takoma Park to Washington Hospital Center because she needed care at a Level 1 trauma center, officials said.

"We were treating her, giving her the best of care, and she was getting everything she needed, but we desperately wanted to find her family," said Karen Levinson, the social worker assigned to the case at the Northwest Washington hospital. "We knew they had to be very, very worried."

D.C. police said they had no missing-person reports matching her description. Prince George's police canvassed the Langley Park neighborhood where she was found, showing her picture to residents. No one recognized her.

Then last week, Washington Hospital Center gave her picture to the media.

William Coissi turned on the TV news in his Northwest Washington apartment Monday evening and saw a report about a Jane Doe who had been hospitalized. Suddenly, a picture of his mother flashed on the screen.

For as long as he can remember, Coissi has worried about his mother wandering off. When he was young, Eloina Affonso sometimes went missing for days, he said. If he came home from school and found her gone, he would get himself something to eat. If she stayed away for several days, he'd go to stay with neighbors or friends.

When she was home, "I would just try to take care of her the best I could," said Coissi, 25. "She gets the past mixed up with the present. She has for a long time. She wouldn't be able to tell you the time of day, her age or her background. She doesn't remember that. It would be confusing for her."

Coissi believes his mother was confused again last month when she wandered away from their apartment. For weeks, he searched her favorite places to walk, mostly around Adams Morgan, inquiring about the woman with the kind smile and the silver braids. He was concerned that she would not be able to communicate on the streets because she speaks only Portuguese and a little Spanish. He said he filed a missing-persons report with D.C. police. He visited shelters and asked friends to look out for her.

The morning after the television broadcast, he and his mother were reunited at the hospital.

"I was relieved when I saw her," Coissi recalled. "She recognized me. She couldn't really express it. She was babbling things like, 'Wow!' and 'That's my son!' in Portuguese. I could tell she was happy to see me."

Prince George's police continue to investigate what happened to Affonso, a native of Brazil who just turned 65. According to Coissi, she left her apartment in the 3500 block of 15th Street on May 14 or 15. She was found May 15 in the 2100 block of University Boulevard.

Meanwhile, Levinson and others at Washington Hospital Center say they are arranging to move Affonso from the hospital to a nursing home. Coissi said he would welcome that change and hopes his mother will adjust.

"She loves to walk," he said. "If she can't walk around outside, it bothers her."