The Calvert County Planning Commission is investigating whether a shopping center in Lusby is in violation of a county zoning ordinance, a finding that could lead the planning body to take the highly unusual step of revoking approval of the project.

In a letter to the developers of the Lusby Center, a commercial project on land owned by the John M. Gott Jr. family off H.G. Trueman Road, an attorney for the Planning Commission said the site plan may have been approved based on "mistaken information."

The mistake, if there was one, concerns the boundary between commercial zoning and residential or office uses.

"This situation, should it turn out to be true, could lead to a proceeding to revoke or rescind the approved site plan," the attorney, John Yacovelle, wrote in the letter, dated June 9. "Of course, if you proceed with construction in the interim, you will do so at your peril."

Gott, who said this week that he was shocked by the letter, said he will not stop construction on the project, which is more than halfway built.

"All of a sudden at the eleventh hour we're getting this surprise out of left field," he said. "Our position is that everything we've done is completely legal and with [the commission's] blessing."

The questions about compliance with zoning are the latest twist in the much-debated development of the Lusby town center.

The leaders of local civic associations complained last month in a letter to county Commissioner Gerald W. Clark (R-Lusby) and local newspapers that the town's master plan had been "tattered beyond recognition" and that "government has failed its citizenry." Art Carson, a commercial real estate broker with O'Brien Realty, whose clients include a rival commercial development in Lusby, filed a complaint last month with the county Ethics Commission about the Lusby Center.

In response, the Planning Commission met in a closed session June 8 to address the project on Gott's land. At issue is whether the master plan forbids commercial development on part of the land where the Lusby Center is located.

The 2002 master plan for the Lusby town center called for a parkway to serve as a line dividing two zoning categories: Land to its west was to be zoned for commercial use, with land to the east zoned for residential and office use. But during the site planning process, the proposed parkway was moved east by up to 400 feet at some points, said John R. Ward, chairman of the Planning Commission.

He said moving the parkway nearly doubled the amount of buildable land on its western side from nine acres to about 17 acres.

"The question is: Did the zoning line move with the parkway?" said Greg Bowen, the county's director of planning and zoning.

Ward said the zoning line could not have moved with the parkway because it would have deviated greatly from the master plan approved by the county commissioners.

"It changes the zoning line so much that it violates the master plan approved by the commissioners," he said. "What [the developers] did was beyond what the Planning Commission had authority to approve."

If Planning Commission members had understood how far the road had moved to the east, Ward said, they would not have approved the site plan for the Lusby Center.

"We didn't know that it really changed. . . . We assumed that it was the same," he said. "I didn't get the picture."

But Gott said that the Planning Commission has been aware of the issue for months and that the zoning officer had determined that the zoning line moved along with the parkway.

"If somebody was going to look at it, it sure would have been nice if they had done it before we poured in millions of dollars," he said.

Construction on the project is about halfway complete, Gott said, and he expects the commercial center, which is to be anchored by a Food Lion supermarket, will open by the end of the summer.

Yacovelle's letter asked Gott to respond within 15 days if he wants to "present evidence and/or argument addressing this issue and possibly laying it to rest." The letter said Gott may also wish to seek an amendment to the zoning ordinance.

Gott said he is not sure whether he will make a formal response to the Planning Commission.

"If he continues to build and doesn't respond, then I guess the county would have to decide how long to wait before getting a stop-work order," Ward said. He said the Planning Commission has not discussed whether it might seek to have the building torn down if it is found to be in violation of the zoning ordinance.

If Gott seeks an amendment to the zoning ordinance, Ward said, the Planning Commission might consider making changes to the entire Lusby master plan.

"We want the town center to work. We had a vision for it," Ward said. "Whether it's been ruined to the point that it's unfixable, I don't know."