"John Urner did a good job for us," Ross said.
Annexation negotiations with the city are in the early stages, he said.
As part of the possible annexation, Petrie Dierman Kughn is asking the city for financial help with utilities and roads, said City Administrator Bruce Zimmerman.
The developer would reimburse the city through property taxes, he said.
Washington County Commissioner Ronald L. Bowers last Tuesday accused Urner of a conflict of interest in representing the city and the developer. Urner said there was no conflict of interest.
Urner said both the city and the developer were aware they shared a law firm.
But Zimmerman said Urner told him on Thursday he had decided it would be better if he no longer represented the developer.
While city officials might have had a concern about sharing a law firm when they start negotiating financial matters with the developer, it was Urner's decision to stop representing Petrie Dierman Kughn, Zimmerman said.
Ross said two to three local firms would be interviewed for the job of representing the development firm on local issues.
Construction on the shopping center at the intersection of Interstate 81 and U.S. 40 is scheduled to begin late next summer or fall and open a year later, Ross said.
It would employ 1,500 people, he said.
The developer has asked for city sewer to serve the shopping center, but county officials want the sewage to go to the county's Conococheague Wastewater Treatment Plant.
Ross said the area is not in the county's sewer district.
Talks with the commissioners about the county extending roads and utilities for the shopping center never came to fruition, he said.