Roger Stone’s arrest for lying to Congress, obstruction, and witness tampering didn’t just implicate the longtime political strategist and Donald Trump adviser.

The charges, filed last week, also suggest Special Counsel Robert Mueller may be getting closer to the president’s inner circle, as the investigation probes whether the Trump campaign colluded with the Russian government to influence the 2016 election.

Tucked into page 4 of the indictment was an intriguing assertion that "a senior Trump Campaign official was directed to contact Stone" to find out more about what emails WikiLeaks was planning to release next. So that unnamed campaign official had to be directed by someone.

As a top adviser to the campaign, Donald Trump Jr. was involved in a number of meetings and projects that have come under scrutiny as part of the Mueller probe and multiple congressional investigations. That could make him the next member of Trump's inner circle to become the focus of the special counsel's investigation.

Congressional investigators are already sounding the alarm that they believe Don Jr. wasn't entirely honest with them when he testified under oath on the Hill. And if he knowingly lied to lawmakers, that would constitute a felony.

Sen. Richard Blumenthal, a Connecticut Democrat and member of the Senate Judiciary Committee, told reporters that he wanted a number of individuals, including Trump Jr., to return to Capitol Hill for another round of testimony to clarify inconsistencies.

"I think many of them should be called back to testify in public, and I hope that will be true of other congressional committees, as well, because behind closed doors, there were questions, serious issues concerning their truthfulness, and that issue pertained particularly to Donald Trump Jr. in a number of contentions," Blumenthal said.