Witthaus acted as a toxicological expert in several sensational poising cases, including the trials of Howard Benham, Martin Thorn, Dr. Robert W. Buchanan, Mary Fleming in 1896, Carlyle Harris, Roland Burnham Molineux in 1900, Albert T. Patrick in 1900, and Harry Thaw in 1907.
Witthaus played a key role as an expert witness in several dramatic poisoning cases, including the trials of Howard Benham, Martin Thorn, Dr. Robert W. Buchanan, Mary Fleming in 1896, Carlyle Harris, Roland Burnham Molineux in 1900, Albert T. Patrick in 1900, and Harry Thaw in 1907.