Authorities believe some of the people who arranged for Porter to fix his performance in two games last season had inside information that prompted them to bet large sums of money against Rozier a year earlier. The emergence of suspicious betting activity on another NBA game demonstrates that the scheme that resulted in Porter’s expulsion—and the government’s investigation—is more expansive than was previously known. The difference this time is that the person who attracted the unusual wagers is far more prominent than Porter, a fringe player who spent his NBA career trying to hold on to a job. Rozier is an established presence who has been a solid contributor in the league for a decade and is partway through a contract that will pay him nearly $100 million. And the government’s investigation will likely continue to grow: Authorities are exploring the gambling ring’s potential ties to college basketball as well, people familiar with the probe said.