Business licensing, individual registration and surety bond requirements for the District, Maryland and Virginia: District of Columbia

License fee: $158/year (Nov. 1-Oct. 31); Minimum age: 18. No registration fee. $5,000 surety bond. Agency: D.C. Business License Office, 614 H St. NW, 20001. (202) 727-7090. Police background investigation. Lt. Jacqueline Simms, Metropolitan Police Department, Room 301, 420 7th St. NW. (202) 727-4459. Maryland

License fee: $400/yr. individual; $750/yr. firm. Minimum age: 25. Registration fee: $50, one-time fee, plus $11 for record check and fingerprinting. Minimum age: 18. $3,000 surety bond/individual; $5,000/firm. Lt. Byron L. Hubble, Maryland State Police, Pikesville, Md. 21208. (301) 486-3101. Virginia

License fee: $550 (first year); $150 yearly renewal. Registration fee: $30 (one-time fee, with a $10 reregistration fee if investigator switches firms). Minimum age: 18. $25,000 surety bond or $100,000 professional liability insurance. David E. Dick, Virginia Department of Commerce, 3600 West Broad St., Richmond, Va. 23230. (804) 257-8500. In Virginia, 1-800-552-3016. For training standards and waivers: Richard N. Harris, director, Virginia Department of Criminal Justice Services, 805 East Broad St., Richmond, Va. 23219. (804) 786-4000. Schools

(Virginia requires all PIs to successfully complete a 44-hour block of classroom training. Investigators have 120 days from when they begin working for a firm to complete the course. The training is not required in the District or Maryland.)

William Smith, Central Training Academy, 7311 Tyler Ave., Falls Church, Va. 22042. (703) 573-6400. Fee: $250.

Howard Miller, Miller & Associates, 2771 Hartland Rd., Falls Church, Va. 22043. (703) 241-1151. Fee: $200. Professional Associations

Maryland Private Investigators Association, Baltimore. (301) 987-9151.

National Association of Investigative Specialists, Suite No. 1, 937 Reinli, Austin, Tex. 78751.

Virginia Private Investigators Association, Burke, Va. (703) 978-0488. Books/Catalogues

Butterworth Publishers, 80 Montvale Ave., Stoneham, Mass. 02180; (617) 438-8464. Interviews and Interrogations, $19.95; Surveillance and Undercover Operations, $19.95.

Washington Researchers Ltd., 2612 P St. NW, Washington, D.C. 20007; (202) 333-3499. Washington Information Workbook: The Encyclopedia of Sources, $75.

Paladin Press, P.O. Box 1307, Boulder, Colo. 80306; (303) 443-7250. Find 'Em Fast: A Private Investigator's Workbook, $12; Practical Guide for Private Investigators, $8.95.

Thomas Publications, Suite 1, 937 Reinli, Austin, Tex. 78751; (512) 452-3877. How To Find Anyone Anywhere, $19.95; Physical Surveillance Training Manual, $12.