| Business | Phone |
| A-1 Polygraph Milwaukee 53214 | (414) 257-1400 |
| Agency One Milwaukee 53209 | (414) 303-4800 |
| Investigative Technologies 6657 N Sidney Pl, Milwaukee 53209 | (414) 228-6560 |
| Pinkerton Consulting 6737 W Washington St, Milwaukee 53214 | (414) 546-4400 |
| Resource Group Private Po Box 26768, Milwaukee 53226 | (414) 463-6645 |