If your main source is court docs and snitch statements, you have to understand most of that is not very credible.
"I am not a snitch," she said during the interview we had the year before she died.
I was humiliated, but also incapacitated by my desire to not be further alienated by becoming a “snitch.”
"informer," 1785, probably from underworld slang meaning "the nose" (1700), which apparently developed from an earlier meaning "fillip on the nose" (1670s). Snitcher in same sense is from 1827.
[origin obscure, although apparently these, along with several other slang uses, both British and US, all refer somehow to the long-billed bird and its habits]