In a few weeks on the job, special counsel Robert Mueller has assembled an elite team of lawyers with expertise in national security, public corruption and financial crimes, suggesting he is taking a broad view of his mandate to probe Russia’s alleged meddling in the 2016 election.

Since being tapped by Deputy Attorney General Rod Rosenstein in May, Mr. Mueller has added 15 attorneys to his staff as well as an undisclosed number of administrative employees, according to spokesman Peter Carr.

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