milk and false positives with ortho-tolidene; legal lynchings
"During the course of his investigations, Hosken discovered in a standard textbook, the warning that traces of heavy metals, especially copper, can stimulate peroxidase activity similar to that of blood. This inspired him to carry out further experiments of his own. Using an orthotolidine solution he tested a number of different substances. With milk, he found that it gave coloration indistinguishable from blood. His tests with a sample of laboratory copper oxide gave him startling results. The reaction was fast and a brilliant blue, the classic blood reaction."
link.
I am not sure what in milk is reacting, but I am very intrigued. Jack Waterford's
examination of the case in 2012 is worth reading in its entirety, but I especially liked the following:
"Most stem from the human error of theory-dependence - focusing on evidence that supports a theory already formed, ignoring evidence that doesn't, making connections that send investigations down certain paths, holding on to theories even after they have been falsified. Duhs shows in case after case how this caused vital clues to be ignored, and investigations marshalled to prove things which were wrong. Triumphant detectives are rarely given to self-doubt.
"It should not be thought that concerns about miscarriages of justice come only from an anti-police brigade. Here in Australia a number of forensic scientists have expressed concerns about the quality of evidence sometimes going before courts, the use of bad procedures, failures of chains of custody, incapacity to replicate results, the use of samples too small to guarantee results, sloppy systems of avoiding contamination and cross contamination, the use of impure chemicals, and the use of equipment which had not been validated or which were known for inaccurate results. As problematic, in some jurisdictions has been an association so close between forensic scientist and investigating police, as well as a pressure of overwork, that presents real risks of undermining the detachment that experts pretend. The scientific method, of course, is ever anxious to test a theory, not least with evidence that challenges it, rather than focusing only whittling facts until they fit the theory. The Chamberlain case is a warning about legal lynchings, and a reminder never to think a case is closed."