Sweeping development plans for a remote area of northern Vermont, a biomedical research plant, a hotel and conference center, an airport runway extension and big upgrades at two ski areas, brought the promise of jobs to a region that has some of the highest unemployment rates in the state.

But new allegations that two businessmen behind the plans misused more than $200 million of about $400 million raised from foreign investors “in Ponzi-like fashion” has brought some of the development to a halt and left state officials, who enthusiastically promoted the projects, feeling betrayed.