The idea of “signature” behavior while committing a crime is that offenders make choices that reveal aspects of their personality. “The killer’s signature is his psychological ‘calling card’ that he leaves at each crime scene across a spectrum of several murders,” says former homicide detective Robert Keppel.
It might be a ritual, a wound pattern, or a tool for achieving a goal. Often, it's sexual or anger-driven. I’ve written more broadly about signatures here.
This blog focuses on knots. A basic book on tying knots will discuss function, form and material. You’ll find knots that loop, hitch, join, bind, slip, slide, stop and constrict.Read more on psychologytoday.com