Douglas Wilson and Randy Booth from A Justice Primer:

In a public setting, it is necessary for the accuser to be prepared to prove what he says. In order to that (is this starting to sound familiar?), he must not be anonymous, he must be accountable to a body for his charges (in case they prove deliberate falsehoods), he must have independent confirmation of what he says (2-3 witnesses). If these conditions do not pertain, a church body is prohibited by Scripture from entertaining the charges (I Tim. 5:19). When authorities unsubstantiated charges, they are not covering anything up. They are being obedient.