Police investigative methods and technology were primitive compared to a few decades later (e.g., neither fingerprints nor blood typing were in wide use), and crime scenes were often compromised by curious onlookers.

According to the Jameses, a number of murders in the period which were assumed by local police to be one-off incidents were actually committed by a single person, probably Mueller, based on about thirty similarities, many of which feature in most of these crimes.

[8][9] In early cases the killer often attempted arson to destroy the house, but gradually abandoned the practice possibly because it more quickly brought attention to the scene.

Bill James noted that nationwide from 1890 to 1912 there was an average of eight murdered families per year, most of which do not share the characteristics reported in media for the crimes attributed to Mueller.

[8] If accurate, these totals would place Mueller/The Man from The Train either just behind or ahead of Samuel Little, the American serial killer with the most confirmed victims, who was convicted of 60 murders and claimed 93.

The murders bear some similarities to the U.S. crimes, including the slaughter of an entire family in their isolated home, the bodies being moved after the killings, a young girl among the victims, use of the blunt edge of a farm tool as a weapon (a pick axe), and the apparent absence of robbery as a motive.

The authors suspect that Mueller, described as a German immigrant in contemporary media, might have departed the US for his homeland after private investigators and journalists began to notice and publicize patterns in family murders across state lines.

[8] In a review for The New York Journal of Books, Bill McClug described The Man from the Train as "an interesting and fascinating albeit rather unknown story, and it is commendable that the authors have chosen to bring it to light.

"[1] In a blurb on the dust jacket for the book's hardcover edition, professor Harold Schechter states the Jameses offered the most plausible explanation to date for the Villisca murders.