Green’s Dictionary of Slang

1. (Aus.) a cadger.

1919

N.Z. Truth 21 June 1/7: He’s a snitcher. You make a fag and for sure he gets yer [...] As he murmers sweetly, ‘Give us the makin’s’.

2. (US) a petty thief.

1930		‘Snitcher’s Blues’ in Botkin Folk-Say 334: O mah babe, way down in Polock town / Where de police an’ de snitchers, dey tore my playhouse down.
a.1948		(con. early 1930s) C. McKay Harlem Glory (1990) 23: I don’t like a woman who’s a little snitcher.