Two-year-old Lindsey Filippi was forever at the heels of her energetic big sister, Nicole, who, at 4, was a hero in her adoring younger sister's eyes, neighbors said.

"The little girl would always push the baby on the swing," said neighbor Luther Williamson. "They learned from each other. They were together all the time."

Howard County police and prosecutors believe they died together, too, in an upstairs bed at the hands of their 43-year-old father, Robert Emmett Filippi, who is charged with strangling them Sunday night.

Still reeling from the news, neighbors and day care workers who knew and loved the girls struggled to cope yesterday by remembering the times they shared with Nicole and Lindsey.

In the absence of scheduled services or other concrete ways to express their grief, people left flowers and balloons on and near the wooden fence bordering the Filippi home on Harmel Drive in Columbia.

The girls' mother, Naoko Nakajima, is making funeral arrangements for her daughters, an assistant to her lawyer said yesterday. Plans have not been finalized.

Nakajima and her husband were in the thick of a divorce and custody dispute, according to court paperwork.

Filippi's fear that his wife would return permanently to her native Japan with the children is documented in divorce filings. A note found in the home addressed to Nakajima said, "You can go back now." The note was introduced at Filippi's bail review hearings Monday.

Because Nakajima is not speaking publicly, her family lives in Japan and Filippi's relatives refuse to talk to reporters, details about the girls was available in fragments.

Neighbors described the Filippi girls as beautiful. They had shoulder-length, straight dark hair and were almost always smiling, Williamson said.

A grandfather of 12, Williamson said he and his wife, Mary, saw the sisters almost daily. The Filippis had lived in a $325,000 two-story home next door for about four years.

"It was nice to see them growing up and loving life ... and then it gets wiped out," he said, shaking his head. "It's still so hard to believe this happened. I'll never understand."

At nearby Children's World Learning Center where the girls spent most of their weekdays, staff members mourned the loss of friends who had been part of their day care center since August.

"They were our little angels," said Patty Taylor, district manager of the center. "We're grieving, too."

Children's World will hold a memorial service and plant a tree in honor of the Filippi sisters in several weeks, Taylor said.

In a written statement about "our girls," provided yesterday, Taylor said she and the staff members "feel this tragedy personally."

"We would describe our Nicole as fun-loving, full of energy and life," the statement said. "Our Lindsey was a special princess that loves everyone."

Out of respect for the family, Taylor said, none of the employees would speak further about the girls or release photos of them.

Luther Williamson said he and his wife used to entertain the girls with wind-up toys and watch them run through the families' adjoining yards in Columbia's Hickory Ridge village.

Nicole loved to pick berries from a vine behind his house, Williamson said.

"'Just eat the blackberries. They're the ones that are ready,'" he recalled telling her.

Mary Williamson, who frequently baby-sat the girls, was too distraught to talk about them, her husband said.

Hours before their deaths, the sisters swam in a tropical-print wading pool and later caught fireflies and played with sparklers in their yard, neighbor Bradley Arnold said.

Arnold and his two children spent Sunday evening on the Filippi deck and were close friends with the family. His 8-year-old daughter and 11-year-old son adored the girls, he said.

"They were a joy - full of energy," Arnold said.

"I don't think Nicole took any walking steps. Anywhere she went, she was running, and Lindsey followed her big sister around."

Sun staff writer Lisa Goldberg contributed to this article.