The surgeon from the southern Russian city of Belgorod, 577 kilometres south of Moscow, was caught on security camera punching a male patient in the face, causing him to fall backwards and die from a head injury.
Russia's Investigative Committee today said the doctor has been detained on the basis of "new information on the crime", without specifying what it was.
It said in a statement said they would ask a court to sanction his pre-trial detention in prison.
The chairman of Russia's Investigative Committee, which probes major crimes, has taken personal charge of the case due to the "large public reaction", the Investigative Committee said today.
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Investigators initially said Saturday that the doctor, identified as surgeon Ilya Zelendinov, remained at liberty but had signed an undertaking not to travel.
The surgeon is being investigated on suspicion of causing death by negligence, for which he could serve up to two years in prison. He has also been sacked from his job.