Find largest connected components AWS Neptune
Solution 1:
Connected component finding queries can be expressed in Gremlin, but whether or not those queries will be efficient, is going to depend on the complexity of the graph. I would start by looking at the Gremlin Recipes document.
You will find several algorithms discussed there.
At very large scale, you may want to export data from the graph and run a Spark job (or similar) to find the fraud rings etc.