Here's the NIV rendition of Leviticus 5:1 -
If a person sins because he does not speak up when he hears a public charge to testify regarding something he has seen or learned about, he will be held responsible.
Here is various commentary on the verse: (Found at this site.)
Keil & Delitzsch:
The first (Leviticus 5:1), when any one had heard the voice of an oath (an oath spoken aloud) and was a witness, i.e., was in a condition to give evidence, whether he had seen what took place or had learned it, that is to say, had come to the knowledge of it in some other way. In this case, if he did not make it known, he was to bear his offence, i.e., to bear the guilt, which he had contracted by omitting to make it known, with all its consequences. ??? does not mean a curse in general, but an oath, as an imprecation upon one's self ( equals the "oath of cursing" in Numbers 5:21); and the sin referred to did not consist in the fact that a person heard a curse, imprecation, or blasphemy, and gave no evidence of it (for neither the expression "and is a witness," nor the words "hath seen or known of it," are in harmony with this), but in the fact that one who knew of another's crime, whether he had seen it, or had come to the certain knowledge of it in any other way, and was therefore qualified to appear in court as a witness for the conviction of the criminal, neglected to do so, and did not state what he had seen or learned, when he heard the solemn adjuration of the judge at the public investigation of the crime, by which all persons present, who knew anything of the matter, were urged to come forward as witnesses
Barnes:
Swearing - Adjuration. The case appears to be that of one who has been put upon his oath as a witness by a magistrate, and fails to utter all he has seen and heard (compare the marginal references. and Proverbs 29:24; Numbers 5:21).
Clarke's Commentary:
If a soul sin - It is generally supposed that the case referred to here is that of a person who, being demanded by the civil magistrate to answer upon oath, refuses to tell what he knows concerning the subject; such a one shall bear his iniquity - shall be considered as guilty in the sight of God, of the transgression which he has endeavored to conceal, and must expect to be punished by him for hiding the iniquity to which he was privy, or suppressing the truth which, being discovered, would have led to the exculpation of the innocent, and the punishment of the guilty.
From what I can see, the major difference between this and KH practice is that the context of Lev 5:1 is very open, a public matter. In KH practice, the reporting is more a matter of secret reporting. Often the elders will keep the informer anonymous , even to the one accused. Indeed, many would say nothing if they couldn't remain anonymous.
Take Care