He was an identity doctor for Wesen that cannot control their inner creature selves. His form constantly ripples rather than fully woges, because he has learned to control his inner Wildermann.
Brinkerhoff's preferred method for helping counter one's Woge was the "talking cure", encouraging Wesen to form support groups and share their concerns as therapy. Brinkerhoff published a book about the "inner man" just before experimenting with chemical therapeutic solutions.
Brinkerhoff's chemical therapeutic solution was made from herbs, spices, and trace amounts of steroids; all of these later confirmed by the Portland Police Bureau not to be illegal substances. The mixture was pumped subcutaneously into the back of the patient's neck, and its purpose was to inhibit neural signals known to promote a Woge.
Unfortunately, presumably due to lack of funds, Brinkerhoff wasn't able to conduct the necessary preliminary tests on the drugs, resulting in him skipping medical protocol and testing them upon his willing test subjects.
Brinkerhoff's initial three test subjects were Larry Mackenzie (a patient of Brinkerhoff's), Alan Evercroft, and Dan Murray. Evercroft and Murray were found and recruited by Larry Mackenzie. Another man, Reynaldo, was approached with the opportunity to test this therapy, but declined since he didn't support "cure-alls".
Tragically, Brinkerhoff's four test subjects (all of the Wildermänner, himself included) encountered the same withdrawal symptom when the level of medicine pumped into the body decreased: they would lapse in such a way that they could not woge back into human form.
Brinkerhoff realized this when he found out his first three subjects had all died from like incidents, and just as he was recording this information, the same happened to him as well, leading to his own rampage and demise.