THE BOOKLET IS A SUPPLEMENT TO A BOOK ON PRETRIAL PROBLEMS OF PROSECUTORS (SEE NCJ-56003), WHICH IS PART OF A SERIES ON PROSECUTORIAL ROLES AND FUNCTIONS. THE CONCEPT OF THE PROSECUTOR AS AN INVESTIGATOR AND THE HISTORY AND DEVELOPMENT OF THE GRAND JURY IN ITS INVESTIGATIVE FORM ARE REVIEWED, WITH PARTICULAR ATTENTION TO APPLICATIONS OF THE GRAND JURY'S POWERS AND TO CONCERNS THAT GOVERN ITS OPERATION IN THE MODERN CONTEXT. FACTORS TO BE CONSIDERED BY PROSECUTORS IN DECIDING WHETHER TO SEEK GRAND JURY INVESTIGATIONS ARE DISCUSSED. PRELIMINARY STEPS IN PLANNING A GRAND JURY INVESTIGATION ARE OUTLINED. THESE INCLUDE SELECTION OF THE GRAND JURY; SELECTION AND COLLECTION OF EVIDENCE; CHOICE, PREPARATION, AND ORDERING OF WITNESSES; SELECTION OF THE PROSECUTING ATTORNEY WHO WILL HANDLE THE INVESTIGATION; AND PREPARATION OF THE EXAMINATION AGENDA. ASPECTS OF THE GRAND JURY INVESTIGATION--SUBPOENA POWER, IMMUNITY, CONTEMPT OF THE GRAND JURY, PERJURY, RULES OF EVIDENCE--ARE DISCUSSED AS THEY BEAR UPON THE PROSECUTOR'S RELATION TO THE GRAND JURY. THE REPORT CLOSES WITH A BRIEF SURVEY OF PROPOSALS FOR REFORMING GRAND JURY PROCEDURES. PROSECUTORS ARE REMINDED THAT, WHILE THE GRAND JURY IS THEIR PREEMINENT INVESTIGATIVE ASSET, THERE ARE OTHER INVESTIGATIVE TOOLS--SEARCH WARRANTS, ELECTRONIC SURVEILLANCE, UNDERCOVER AGENTS, CONFIDENTIAL INFORMANTS--AVAILABLE TO THEM. A BIBLIOGRAPHY OF ARTICLES AND CASES IS INCLUDED. (LKM)