As many as 20 correctional officers who work at the federal detention center where Jeffrey Epstein died by suicide received grand jury subpoenas last week relating to an investigation into his death, according to a source with knowledge of the situation.

Investigators are trying to recreate the events that happened on the night Epstein died nearly two weeks ago at the Metropolitan Correctional Center in New York, the source said.

For example, investigators want to talk to the lieutenants who were in charge that night to get details on rounds that were not made, the source said. Epstein was supposed to be checked on regularly.

More subpoenas could be in the works as the investigation widens, the source added.

CNN has reached out to the Department of Justice for comment.