A Minnesota man bludgeoned his co-worker to death with a sledgehammer because he simply didn’t like her, and admitted to planning the killing “for some time,” authorities said Wednesday.

David Delong , 40, was charged with second-degree murder for the killing of Amber Czech, 20, at their shared workplace, Advanced Process Technologies in Cokato, Minn., the county prosecutor said in a statement.

Delong walked over to Czech’s work station , picked up a sledgehammer and struck her at least five times, Wright County Attorney Brian Lutes said in charging documents. The brutal attack was captured on surveillance video at the factory about 45 miles west of the Twin Cities.

Prosecutors said Delong then told another co-worker, “I hit her with your hammer , she is by your toolbox, she is g

See Full Page