"The Russian government interfered in the 2016 presidential election in sweeping and systematic fashion."
"First, a Russian entity carried out a social media campaign that favored presidential candidate Donald J. Trump and disparaged presidential candidate Hillary Clinton. Second, a Russian intelligence service conducted computer-intrusion operations against entities, employees, and volunteers working on the Clinton Campaign and then released stolen documents. The investigation also identified numerous links between the Russian government and the Trump Campaign.......
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the investigation established that the Russian government perceived it would benefit from a Trump presidency and worked to secure that outcome, and that the Campaign expected it would benefit electorally from information stolen and released through Russian efforts"
https://www.justice.gov/storage/report.pdf
This wasn't a Congressional investigation and the issue is far from dead. Congress has every right to investigate the connection.