On page 84 of The Case Book of Emily Lawrence, Emily picks up a murder weapon, looks it over carefully, and takes it back to her cabin. She and Charles were traveling just off the coast of Connecticut, not on the open sea. The year is 1882.
In 1880, she tramples all over a crime scene, walking on the carpet, scraping at the marks on a windowsill, scuffing through the snow were the footprints may point to a possible perpetrator.
In the unpublished stores, she moves a body before the police have been notified. I'm sure she does endless other things we know better than to do today.
I always get nervous when one of my characters contaminates a crime scene, or fiddles with evidence. I've been to endless presentations on crime scenes, and the first and foremost principle is that you don't fiddle with them. I have learned well, but in Emily's day there was no such thing as contaminating the crime scene.
No one thought much about the sites that we now know hold clues to what happened, and even who did it. Police were there to stop crime, not to solve it.
If you have read any Sherlock Holmes you know that the cops are routinely astonished at Holmes request that nothing be touched until he arrives. The first Holmes story A Study in Scarlet was published in 1887 and gives a pretty good picture of how the police acted at the time. The Metropolitan Police, Criminal Investigation Department of Scotland Yard was formed in 1854 but didn't become official until 1878.
Most of the police force in Washington was composed of patrolmen, not detectives. Cambridge had three police stations at the time but no detective division. I had to mess around with history some to give Emily officials to work with in the police.
Edmond Locard, famous for Locard's exchange principle, wasn't born until 1877.
Still I am stuck in the present day and it is hard for me to make my protagonist act in a way that counters all my modern sensibilities.
I'd be interested to know if any of you are bothered by things in your writing or reading that, while all right for the time or place, aren’t modern day best practices.