The long and bitter battle over the expansion of one of Washington's most elite nursery schools -- already more than two years at full boil with both school and neighborhood lawyered up, employing traffic consultants and swapping closely argued communiques -- has reached a new level.

A private detective. An all-night stakeout on Columbia Road NW. Furtive photos. Allegations of secret romance tainting the regulatory process.

Supporters of the National Child Research Center in Cleveland Park -- which once educated Franklin Roosevelt's grandson and Lyndon Johnson's daughter -- are crying foul at the tough tactics.

"We are saddened and offended that the neighbors have stooped this low in their efforts to keep the school from upgrading and modernizing facilities and adding 10 3-year-old children to its rolls," said Lucretia Adymy Risoleo, chairwoman of the nursery school's board of trustees.

But opponents of a $3.5 million plan to double the facilities on narrow Highland Place NW say they had no choice but to reveal evidence of a "close personal relationship" between the chairman of the city panel considering the plan and a woman who until recently was on the nursery school's board. The chairman voted in favor of the expansion, which was approved in April.

"It's a matter that goes to the integrity of the process," said William Jeffress, a lawyer hired by residents challenging the nursery school. "It's an unfortunate fact that [private] investigators are necessary, but they are used all the time."

When last we checked in with the controversy 17 months ago, Cleveland Park was badly riven over the fabled nursery school where nine months' tuition runs to $12,000 a year. Most of the immediate neighbors were against the expansion, arguing that the 171-student nursery school already enrolled too many children and caused severe traffic congestion. Many others in Cleveland Park supported the preschool, noting that it hadn't increased enrollment or renovated in years. Families on opposing sides awkwardly crossed paths at neighborhood functions or at the fancy private elementary schools where the nursery school's graduates go.

The row has only intensified.

"This has gotten so distasteful," said Ana Evans, an expansion opponent. "At this point, what drives me is not so much the NCRC anymore but the general sense of injustice at how the process can be so corrupted."

On Monday, proving that in Washington even a zoning fight can be transformed into film noir, the opponents filed affidavits and photos with the city Board of Zoning Adjustment offering what they said is "incontrovertible evidence" that Board Chairman Geoffrey Griffis had a relationship with Claire Bloch, who in April stepped down after several years on the nursery school board. (The filing was first reported this week by Channel 4.)

Enter Darryl Hess, licensed P.I.

In an affidavit, Hess said he watched the two enter Griffis's residence on Columbia Road at 8:26 p.m. June 4. They emerged at 9:25 a.m. the next day, he said.

"Griffis was carrying two beach chairs over his right shoulder," Hess said. "Bloch was carrying children's beach toys in her right hand . . . and a tennis racquet in her left hand. Griffis opened the rear hatch of Bloch's minivan and they both placed the items into the vehicle. Griffis rubbed Bloch's right shoulder using both hands and then kissed her. They walked to the driver's side door, where they kissed again."

Hess was packing a camcorder and shot video of the two outside the residence. Five photos from the video are attached to the affidavit.

In another affidavit, resident Ana Evans said she witnessed Griffis and Bloch having "an extensive animated conversation" on or about Jan. 23 outside Georgetown Day School, where Griffis had a daughter and Bloch had a son in the same first-grade class. Evans also has children at Georgetown Day.

Earlier in January, the zoning panel had voted 3 to 1 against the preschool's expansion, with Griffis in the minority. But later the panel voted unanimously to revisit the issue, and in April the vote was 3 to 1, with Griffis in the majority, to approve the physical expansion, but not the addition of 10 children.

The opponents argue that Griffis persuaded his colleagues to take the second look and swayed the vote for the expansion. They say he should have disclosed his relationship with Bloch and recused himself. Now they say the board should deliberate again without Griffis's influence.

Griffis, who has been divorced for several years, declined to discuss his relationship with Bloch in detail in an interview yesterday. He noted that the private detective's pictures were taken months after the vote on the expansion.

Bloch said in a telephone message to a reporter that she did not care to discuss her personal life. She has been separated from her husband since last fall, before any question of a relationship with Griffis arose, according to people who know her.

"There was nothing to disclose while this case was proceeding," Griffis said of his relationship with Bloch. "My personal relationships have no influence or bearing on any of the applicants that I see."

He said he routinely recuses himself when cases involving his architectural practice come before the board, and he said board members act independently of his influence.

As for his animated conversation with Bloch outside Georgetown Day in January, he said, "I walked out of GDS after the Martin Luther King assembly. I imagine we were all animated -- we had just watched our children put on a two-hour performance."

Jeffress, the lawyer for the opponents, said, "If his view were that this kind of relationship didn't require a disqualification, we respectfully disagree."

The zoning adjustment board will vote Tuesday on the opponents' motion to exclude the chairman and vacate the approval of the expansion. Griffis said he will recuse himself from the vote to recuse him.

Staff researcher Bobbye Pratt contributed to this report.

Parents drop off their kids at the NCRC school along Highland Place. Most neighbors oppose a $3.5 million planned expansion.