Metz died earlier this month from cancer at the age of 79. He was a five decade veteran of Wall Street.
"How Stocks Are Manipulated" was originally published in 1980 by Macmillan Publishing under the title, "Street Fighting at Wall and Broad: An Insider's Tale of Stock Manipulation". It was republished, with its current title, in 1987 by Richardson Snyder Press. For both titles Metz used the pen name, Marchand Sage.
Many of the techniques outlined in the book would have crossed the line of Securities & Exchange Commission regulations. I suspect Metz employed many of the techniques in his own market operations. The SEC never came close to being aware of, or investigating, Metz's operations.