As she turned down Seventh Street NE toward the church, the chill autumn wind whipping her coat behind her, her little baby Billy bundled in her arms, Donna Posey recalled, "I was just really scared, scared of what I was about to do."

Walking slowly up the stairs to the playground, she stepped inside the squeaky iron gate at the Pilgrim Baptist Church and set her year-old boy down, primping his light blue snowsuit and Winnie-the-Pooh pajamas one last time. She put a bottle of milk in his mouth, and kissed his cheek. "I said, 'Goodbye, Billy,'" and she left.

Donna Posey, 21, left her third-born child on that asphalt city playground Monday, near the tidy neighborhood of row houses close to Gallaudet College where she grew up. It was not the first time she had abandoned a child.

Two years earlier, she left her eight-month-old daughter in a restroom in another neighborhood church with a note attached to her shirt asking someone to find her little girl a home because Posey could no longer care for her.

Yesterday, after a long, strained silence during a telephone interview, Posey said, "I know what I did was wrong and I shouldn't have done it, but I had a good reason for doing it . . . . I know I should have learned from [the first time], but I just have problems.

"It's not like I planned it or anything, I just sort of decided to do it, I guess . . . . All I want to say is if it is possible for me to get him back, I'd like to have him . . . . I just wanted to find him a good home."

Billy was found at about 3 o'clock that afternoon by a neighbor who was delivering The Watchtower, a newspaper published by the Jehovah's Witnesses. The woman gave the baby to police, who in turn took it to St. Ann's Infant and Maternity Home in Hyattsville, where he remains today in the custody of the District Department of Human Services. Further police investigations and court proceedings will determine the child's fate.

Posey's older sister, who has custody of the first abandoned child, saw the boy's picture on television and identified the child and his mother.

Posey wouldn't say during a brief and strained telephone interview yesterday why she abandoned Billy. Her next door neighbor and long-time friend, Robert Oesby, 22, said Posey had been moody for some time. "She's going through a mental thing right now. She sits on the steps outside her house a lot, her head down, like she's in another world. Not too long ago she told me she tried to kill herself," he said.

Posey is a graduate of Dunbar High School. She lives on the 600 block of L Street NE with her mother, a nurse, her stepfather, a deliveryman, and two younger sisters and, until she abandoned Billy, her two babies, age one and two.

Neighbors know her as someone who "went to school, didn't go out much, didn't hang on the streets with the rest of the neighborhood. She never smoked or drank, and there was no violence or cussing about her either," said Kevin Dickens, another long-time friend.

When she was pregnant, Oesby said, Posey "kept herself hid. She didn't want anyone to know . . . . She told me she wanted to work, that she got bored sitting around the house with nothing to do."

Dickens said recently Posey had been interested in photography, that she wanted him to be her model.

"She is good people, but sometimes, well, I don't know. One day she'll say hello to you and the next she'll just walk on by like she doesn't know who you are."

"She's just got a lot of things on her ming," Oesby said. "She needs someone to talk to, to help her out."