320 ILCS 20/4.2
Any mandated reporter who makes a report or any person who investigates a report under this Act shall testify fully in any judicial proceeding resulting from such report, as to any evidence of abuse, abandonment, neglect, or financial exploitation or the cause thereof. Any mandated reporter who is required to report a suspected case of or a suspicious death due to abuse, abandonment, neglect, or financial exploitation under Section 4 of this Act shall testify fully in any administrative hearing resulting from such report, as to any evidence of abuse, abandonment, neglect, or financial exploitation or the cause thereof. No evidence shall be excluded by reason of any common law or statutory privilege relating to communications between the alleged abuser or the eligible adult subject of the report under this Act and the person making or investigating the report.
320 ILCS 20/4.2