Scotland Yard investigators staged their largest-ever crime scene reconstruction Monday, summoning more than 200 members of the public back to an East London park to try to re-create the setting on that morning of Feb. 3, when a Virginia woman was fatally stabbed while jogging.

An actress played the role of Falls Church artist Margaret Muller, right down to donning green fleece jogging clothes similar to those Muller, 27, was wearing when she was killed on a pathway between the park's rose garden and a playground.

Investigators said the reconstruction opened "several new lines of inquiry," and early yesterday they arrested an 18-year-old Hackney man. But after 12 hours in custody, the unidentified man was released. Authorities said he is not considered a suspect, but he has been ordered to report back to police next month.

Muller, 27, a graduate of George Mason University who went to England in 1998 for postgraduate studies, was stabbed multiple times as she jogged in Victoria Park near her home -- an attack that investigators described as frenzied. Passersby heard her screams and found the body.

Scotland Yard would not say what prompted yesterday's arrest but said investigators obtained significant new leads after Monday's reconstruction, the largest in the organization's history. Officials said the exercise involved more than 300 people, including police and other officials.

"Everyone was put in the same place and asked to reenact what they did," said Alastair Campbell, a spokesman for New Scotland Yard. "It generated a lot of new interest in the case and a lot of calls."

Muller's body was found on the park's east side. Investigators were able to identify her and notify her family through a cell phone found at the scene.

Contacted yesterday at her home in Falls Church, Muller's mother, Eileen, 60, was unaware that an arrest had been made.

"If . . . we return to England to see a trial, that's what I want most out of this," she said.

Margaret Muller moved to London to study at the Slade School of Fine Art, part of University College London, where she was awarded the Melville Nettleship Prize, one of Britain's most prominent awards for figure composition. Her formal art training in the Washington area included summer classes at the Corcoran School of Art.

Eileen Muller said her daughter lived alone in Hackney, where she had moved in September. The neighborhood is an artists' colony, mixed in with public housing and expensive Victorian homes, according to wire reports. Muller supported herself by teaching and illustrating children's books, her mother said.

Eileen Muller said she worried that her daughter's new neighborhood was dangerous. "She wanted her own place," she said. "It had a skylight, so she could paint; but the area was no place for her to be coming in and out alone.

"It was a terrible attack," she said softly, looking outside at some blossoming bulbs Margaret had brought home from Holland, their green stems just beginning to peek out of the hard, snow-covered ground. "She'd already accomplished a lot as an artist," Muller said. "Her paintings were very beautiful."