The precise meaning of the word "Banking" is trust. The business of banking evolved several centuries ago, in whatever the form it took at that time. Immaterial of the structure of comprehensiveness, the "banker" behaved and conducted the business in a manner that the trust placed in him and his business by the general public, the sovereign, the policy makers and the business community did not wean off or deteriorate at any time.
Accepting money as a deposit, earned or received through illegal sources such as crime, prostitution, pilfering by persons with authority, fraud, robbery or terrorism is considered anti-social and probably viewed as helping or encouraging those culprits to continue such activity in the future as well. Knowingly or unknowingly aiding and abetting to launder dirty money and mix them with money in circulation is a punishable offence. Tipping off or advising a money launderer to take away dirty money and hide from the law is also a criminal and punishable offence.