How does the device called a red herring typically function in a detective story

A red herring is a misleading clue

Explanation:

An example of a red herring in a dective story could be a person who doesn't have an alibi (or refuses to say where they were during the time of the crime) - it leads the audience (and detective) to believe they are guilty, when in fact they weren't.

she swerves to avoid the turtle.