Nearly six months after sustaining serious head injuries in a skiing accident, the 45-year-old Schumacher left a French hospital last week and was transferred to neighbouring Switzerland to continue his recovery. He is no longer in a drug-induced coma.
Schumacher's manager, Sabine Kehm, said in a statement on Monday that notes made about the German's case have been stolen, and threatened to sue any publication willing to use them.
Kehm said: "We cannot judge if these documents are authentic. However, the documents are clearly stolen. The theft has been reported."
Schumacher's office will "press for criminal charges and damages" if the documents and data are made public, Kehm said.