Former special counsel Robert Mueller’s Wednesday testimony before Congress hopefully will be seen as the beginning of an overall impeachment proceeding–rather than the end of the investigation of Donald Trump.

That’s according to Rep. Eric Swalwell of California, a Democrat who took part in questioning Mueller as a member of the House Intelligence Committee.

“I think success is that the American people will view this as volume one — I’m sorry, that the American people will view this as Act 1, not Act 3. And as they heard names today like Manafort and Kilimnik and Gates, they will want to know, well, let’s hear more about that, and that those witnesses will start to come forward,” Swalwell said, referring to former Trump campaign manager Paul Manafort; Konstantin Kilimnik, a Russian political operative with connections to Russian intelligence; and Rick Gates, Manafort’s onetime associate. “I think we should have an impeachment inquiry and those are the next witnesses we need to hear from.”

Mueller spent some seven hours testifying about his two-year investigation Wednesday on Capitol Hill, spending time with both the House Judiciary and Intelligence committees.