(a) The need for prompt action after an offence has been discovered or reported to ensure that biological materials that are subject to putrefaction (sperm and blood) do not deteriorate;
罪行被发现或举报之后必须迅速行动，以保证可腐化的生物物质(精液和血液)不致变质； 分析DNA的方法因国家而异，甚至因实验室而异。