Adam Clarke on Jeremiah 41:7

Slew them - He kept the murder of Gedaliah secret, and no doubt had a band of his assassins lodged in Mizpah; and he decoyed these fourscore men thither that he might have strength to slay them. He kept ten alive because they told him they had treasures hidden in a field, which they would show him. Whether he kept his word with them is not recorded. He could do nothing good or great; and it is likely that, when he had possessed himself of those treasures, he served them as he had served their companions. Grain is preserved to the present day in subterranean pits, called mattamores, in different parts of the east.