Special counsel Robert Mueller’s investigation has started asking witnesses about Jared Kushner’s role in the firing of FBI Director James Comey, and Kushner has handed over documents to Mueller’s team in the last few weeks, according to a new report.

The focus on Kushner, a senior adviser and President Trump’s son-in-law, is a sign that Mueller is looking more closely at the decision to fire Comey as part of its investigation into whether the White House obstructed justice, CNN reported.