| Business | Phone |
| D C Fire & Arson Investigators 4th & Hobart Pl Nwamp;, Washington 20001 | (202) 723-5847 |
| Associated Investigators Inc 1100 15th St Nw # 300, Washington 20005 | (202) 638-2939 |
| Becnel Investigations Llc 733 15th St Nw, Washington 20005 | (202) 638-5000 |
| Brown Investigative Group 601 Pennsylvania Ave Nw # 900s, Washington 20004 | (202) 434-8282 |
| Brown Investigative Group Inc 1101 Pennsylvania Ave Nw, Washington 20004 | (202) 756-2256 |
| Candor Services 733 15th St Nw, Washington 20005 | (202) 737-4560 |
| Capital Investigative Svc 623 E St Ne, Washington 20002 | (202) 347-4980 |
| Carter Co 4418 Macarthur Blvd Nw, Washington 20007 | (202) 333-8037 |
| Center For Investigative 529 14th St Nw, Washington 20045 | (202) 637-8885 |
| Cii Title 733 15th St Nw # 700, Washington 20005 | (202) 789-1581 |
| Davis Investigative Svc 400 7th St Nw, Washington 20004 | (202) 628-1255 |
| Employment Investigations 1825 Connecticut Ave Nw, Washington 20009 | (202) 265-3701 |
| International Society Of Air Washington National Airport, Washington 20001 | (703) 521-5195 |
| Georgetown Group Inc 1041 Paper Mill Ct Nw, Washington 20007 | (202) 338-4521 |
| Global Options 1615 L St Nw # 300, Washington 20036 | (202) 293-2490 |
| Hewick Investigative Svc 419 7th St Nw # 401, Washington 20004 | (202) 628-6666 |
| Hickey Miller & Bailey 1776 K St Nw, Washington 20006 | (202) 833-2488 |
| Investigative Group Inc 915 15th St Nw # 500, Washington 20005 | (202) 789-7700 |
| Investigative Services 1301 20th St Nw, Washington 20036 | (202) 452-9864 |
| Kroll Associates 1000 Vermont Ave Nw # 800, Washington 20005 | (202) 371-6777 |
| National Capital Investigative 419 7th St Nw # 401, Washington 20004 | (202) 393-6565 |
| National Protection Agency Inc 1050 17th St Nw # 600, Washington 20036 | (202) 628-0651 |
| Oso Group Ltd 2121 K St Nw # 800, Washington 20037 | (202) 293-9799 |
| Smith Brandon Intl 1155 15th St Nw # 1002, Washington 20005 | (202) 887-9363 |
| Superior International 1221 Girard St Nw, Washington 20009 | (202) 882-6903 |
| World Access Investigative Svc 3005 Bladensburg Rd Ne, Washington 20018 | (202) 636-9333 |
| Watkins Investigations 3702 14th St Nw, Washington 20010 | (202) 726-7557 |
| A Capitol Process Svc 1827 18th St Nw, Washington 20009 | (202) 667-0050 |
| A-National Security Invstgtns 4000 Albemarle St Nw, Washington 20016 | (202) 966-2551 |