CrimeStoppers
CrimeStoppers of the Lowcountry is a completely anonymous route to get an investigation started. Usually, they are not who you would call for something urgent, but if they get urgent information they will act on it. They have three reporting methods.
Tip Number
First is by simply calling 843-554-1111. Your call will either go to the local call center office. They will generate a "Tip number" for you to write down. Any information you give will be logged under this same tip number. They do not write down any references you might make which would identify you ("my neighbor", "the guy upstairs", "my ex-husband", etc).
They, in turn, contact the involved agencies who then investigate the tip to its conclusion, hopefully an arrest. The CrimeStoppers board then uses a computer program to determine the dollar value of the tip based on several factors. If/when you hear of an arrest being made, you call back to 843-554-1111, tell them your tip number. They will advise if your tip was used to make the arrest, how much the reward is if any, and instructions to claim it.
Instructions
The instructions vary, but maybe to go to a particular business, ask for the manager, tell him/her the tip number, and you walk out with the cash. No signatures, no pictures or video, no receipts.