The Prosecutor's Office decided to expand the investigation into Oliver Reimann.
Previously, officials investigated only the possession of a small amount of narcotic substance.
Now, intentional intoxication is also being investigated.
Prosecutor Liset Rohi said that Reimann may have added narcotic substances to others' drinks.
This can cause health damage.
Rohi explained that such acts may be related to sexual crimes or property crimes.
Last week, the Estonian Drama Theatre terminated Reimann's employment contract.
The theater director Hendrik Toompere Jr. said that Reimann's actions damaged the theater.
He emphasized that the theater must protect its actors and team.
On August 25, Reimann admitted that he had added prohibited substances to his colleagues' drinks.
On the same day, the Prosecutor's Office initiated criminal proceedings against him.
Reimann also claimed in a post that he had discussed the incident with theater management before joining the Drama Theatre.
In May, the theater announced that Reimann would join them.