the.com/paper trail

means The chain of documents, receipts, and records that reconstructs who did what, when, and often why.

from A 20th-century American coinage, literally picturing paperwork laid down like a trail of breadcrumbs — invoices, memos, checks — that investigators or auditors can follow backward to retrace someone's steps. It entered wide use alongside the growth of bureaucratic record-keeping and became a journalism and detective-work staple, especially from the mid-1900s on, as 'follow the paper trail' turned into shorthand for proving wrongdoing through documentation rather than testimony.