House Intelligence Committee Chairman Adam Schiff defended holding testimony behind closed doors in the impeachment inquiry he's heading up against President Donald Trump, likening this phase of the investigation to a "grand jury."

"We want to make sure that we meet the needs of the investigation and not give the president or his legal minions the opportunity to tailor their testimony and in some cases fabricate testimony to suit their interests," the California Democrat said Sunday on CBS's "Face the Nation."

Schiff said they may call some or all of the witnesses to return to testify in public later, though that might not include the whistle-blower who triggered the impeachment fight in the first place.