Gumshoe

[Becky]

An old slang term for a detective or investigator (police-affiliated or private). Variants include dick or private dick, the connotations of which were not meant to be obscene.
Shoes in the late 1800s were made of gum rubber - the soft-soled precursors of the modern sneaker. The phrase to gumshoe meant to sneak around quietly as if wearing gumshoes.
Gumshoe man was originally slang for thief, but by about 1908 the term gumshoe was used to refer to a police detective, and the term has stuck ever since (pun intended).

[Tanya Shivari]

Slang; Detective. Someone who spends excessive time investigating criminal activity

[Greta]

[a rubber] [soled] shoe or a rubber [boot]

a [detective]

a police officer

to walk [stealthily]

[Michiko]

In the past, it was once known as a [detective] or a [slueth]. Now a slueth has become known as a slut, hence [gumshoe]! They have the same meaning once again!

[Donald Trump]

Gumshoe refers to a cop and also a [private detective], like [Sam Spade]. If you walk the streets looking for clues long enough you get gum on your shoes. [Gumshoes] dont wear
sneakers.

[Tina]

informal for detective (= someone whose job is to discover facts about a crime)