Developer Leo Bruso, seeking county approval to build eight luxury homes on about 10 acres along the Potomac River where slaves may be buried, will conduct an underground survey of the site to see if there are unmarked graves.

The Prince George's County Planning Board asked him to survey the property, part of a 23-acre parcel in Fort Washington.

Though the panel recommended he use ground-penetrating radarnoninvasive electronic equipment used to locate graves and buried pipes, Bruso said Monday that details of the study are still being worked out and that other techniques may be used. No date for the search has been set.

Bruso voluntarily conducted a radar survey on two of the eight lots last month, but the Planning Board asked him to examine the entire property. He said he would do so "as soon as possible."

The initial survey, which covered a part of the property where a cemetery was excavated two years ago, found no "evidence that there must be unmarked graves" in the area, according to the surveyor's report. But it detected unexplained underground signals, which some neighbors say could indicate possible burial sites.

Planning Board members had not seen the results of that study before requesting the survey.

Bruso said he was unhappy about having to do the more comprehensive search, but would comply with the panel's suggestion that Maurice Thomas Jr. -- an expert in local African American history who also has knowledge of ground-penetrating radar -- assist in the effort.

The prospect of the new survey pleased some neighbors.

"I think the Planning Board realized there was this possibility [of graves], and their decision was the right one," said Fort Washington resident Dawn Davit, president of the Potomac Valley Citizens Association and a leader of efforts to limit development of the property.

"I think once and for all, with properly supervised technology, we will know if there are other burials."

Bruso's land once was part of a 500-acre plantation where slaves toiled. According to local oral tradition, slaves are buried somewhere on the 23-acre site. In archaeological digs over the course of several decades, thousands of Native American artifacts have been found, but no graves.

Bruso has asked a Prince George's County Circuit Court judge to revoke a County Council decision last year designating the 23 acres as the "Broad Creek Archeological Site." That designation requires special approvals before any grading or construction is permitted. Judge Steven I. Platt, who recently heard arguments in the matter, said he would not issue a ruling until late June at the earliest.

Bruso is also trying to rezone the rest of his land, about 13 acres subject to restrictions because they are part of the Chesapeake Bay Critical Area. Those restrictions allow only one house per 20 acres. Zoning hearing examiner Maureen Epps Webb is weighing the request. She did not return a call seeking additional information.

The possibility of slave or Native American remains on the land worried Planning Board members at a recent board hearing.

"I am very concerned that we are not building on the top of African American graves or Native American burial sites," said board member James F. Harley.

Some area residents said they would like to see the county or state purchase the land and create a local heritage site.

Bruso's opponents said he risked that heritage on a damp June morning two years ago when -- with neighbors watching from behind a fence -- he oversaw the backhoe excavation of a well-marked 1820 family cemetery on the property.

The five known graves on the site were those of former plantation owner Dennis Lyles and his children. The children's graves were in a line parallel to Riverview Road, their father's slightly behind them to the west. Although no coffins or skeletal remains were recovered, except for a possible bone fragment and nail fragment, five boxes of dirt were ceremonially reburied in a local churchyard.

One neighbor, Ellen Konzman, told board members she had found evidence of a second cemetery along a southern fence line: a marker carved with a cross similar to those used to mark the corners of burial plots.

Konzman and others also cited the most recent U.S. Geological Survey map, which shows two cemeteries on the property, one where the Lyles graves were located, the other at the land's southern boundary.

Bruso produced a letter from a Geological Survey official stating that the map was erroneous and that future editions would be changed. The developer also had a number of supporters at the hearing, including his attorney, Thomas Haller.

"The goal is to create the finest community in Prince George's County," said Haller, who emphasized that Native American artifacts are not unique to his client's land but are found frequently along the Potomac.