Summary: When first introduced, the SLUTH method for magnetic interpretation was illustrated by manual example. It was necessary to calculate the slope of the contour curves and then join the locations where the slope was the same with a straight line. These lines converged at the source location and depth. We have automated that process by using the least squares technique to draw the lines. The magnetic source where the lines converge is found by first determining the location where the vertical straight line occurs and then the average depth where all other straight lines cross this vertical. By automating this process one can survey long flight paths and detect all areas of interest quickly and efficiently. The method gives excellent results on synthetic data. On field data, the results are more variable. In a location where there is a strong anomaly, the interpretations are consistent with those obtained by other workers.