The Probation Act of 1925 gave U.S. district courts the power to suspend the sentence of an individual convicted of a crime not punishable by death or life imprisonment, and place that individual on probation. The statute also allowed district judges to appoint probation officers who would notify convicts of the terms of probation, supervise them during the probation period, and make reports to the court regarding their conduct to aid the court in determining whether probation should be terminated or extended. 

See also:

Court Officers and Staff: Probation and Pretrial Services Officers