Incidentally, GPR normally cannot indicate actual skeletal remains. It shows anomalies under the soil, which means anything denser than the soil. Old skeletal remains or pieces of wood are not denser and usually do not show up. The only blips you might see would be from metal on a casket or from some other denser material that was buried.
And even these things you only see as an ambiguous blip of light. If you see a set of blips in a row when doing an old cemetery, you can probably assume you have a row of burials and that they probably were marked at one time or another. It may not have been much of a marker, but they were identified individually.
There is no way they can make this “mass burial” assertion without an excavation (called “ground truthing”) and they know it. And they know they’re lying, so don’t expect any excavations any day soon.
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