Procurement is one of the main forms of acquisition of the Federal Government and are subject to fraud and corruption. In this context, many institutions such as the Brazilian Office of the Controller General try to identify fraud evidences, e.g., use of queries in databases with information about partnership of companies owned by the same group of people to simulate competition. However, many of these queries are manual or limited by the use of information systems databases. This paper explore the benefits of using graph NoSQL databases to identify the relationships between companies to detect fraud in procurement. A case study was carried out to validate the use of NoSQL databases using companies' partnership information based on queries defined by the CGU's auditors.