Federal prosecutors, capping a yearlong investigation, are preparing to file criminal charges against managers of two Bear Stearns Cos. hedge funds whose collapse helped mark the start of the credit crisis.

The U.S. Attorney's office in Brooklyn is slated to complete interviews of witnesses and other key people in the case this week, and has indicated to lawyers with interest in the case that indictments could be imminent, according to people familiar with the matter.

The...