Chicago (CNN) ISIS-related investigations constitute a majority of the 900 investigations the FBI is conducting nationwide of suspected homegrown violent extremists, a federal law enforcement official said Friday.

FBI Director James Comey made mention of the total number of inquiries at a meeting in Chicago on Friday morning.

The law enforcement official said that number includes a range of people, from those suspected of possibly plotting to those simply consuming a diet of ISIS propaganda.

Previously, Comey and other FBI officials have only said there are "hundreds" of such investigations.

Comey told congressional hearings this week the number of Americans suspected of trying to travel to join ISIS has slowed to a trickle in recent months, though it's not clear if that's a long-term trend.