When it appears to the Attorney General that a person has engaged in, is engaging in, or is about to engage in any act or practice declared to be unlawful by this article, or when he believes it to be in the public interests that an investigation should be made to ascertain whether a person in fact has engaged in, is engaging in, or is about to engage in any act or practice declared to be unlawful by this article, he may execute in writing and cause to be served upon that person or any other person who is believed to have information, documentary material or physical evidence relevant to the alleged or suspected violation, an investigative demand requiring such person to furnish, under oath, a report in writing setting forth the relevant facts and circumstances of which he has knowledge, or to appear and testify or to produce relevant documentary material or physical evidence for examination and copying, at such reasonable time and place as may be stated in the investigative demand, concerning the advertisement, sale or offering for sale of any goods or services or the conduct of any trade or commerce that is the subject matter of the investigation.