snitch (n.) Look up snitch at
"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.
snitch (v.) Look up snitch at
1803, "to inform," from snitch (n.). Meaning "to steal, pilfer" is attested from 1904, perhaps a variant of snatch (v.). Related: Snitched; snitching.