Test case prioritization and selection techniques can lead to early detection of faults and can also enable more efficient usage of testing resources. The available methods of test case selection and prioritization suffer from one or several weaknesses. For example, most of them are only applicable at unit level and do not consider the increasing complexity when subsystems get integrated, especially in the context of embedded system development. Furthermore, the existing methods do not take into account results of current test execution to identify and optimize order for rest of the current execution (i.e., they are not online). In this paper, we propose a tool-supported framework, as an online decision support system (DSF), for prioritizing and selecting integration test cases for embedded system development. DSF provides a complete loop for selecting the best candidate test case for execution based on a finite set of criteria. The results of multiple case studies, done on a train control management subsystem from Bombardier Transportation (BT) in Sweden, demonstrate how our approach helps in a systematic way to select test cases such that it can lead to early detection of faults while respecting various criteria. We are also working towards proposing a customized return on investment (ROI) metric to quantify the economic benefits in optimizing system integration testing using our proposed DSF.