The German doctor, who worked in palliative care, is accused of killing four patients who visited the health center in June and July.
Then the 39-year-old, with mixed success, tried to set fire to their home, reports say AP.
The first case occurred on June 11 when firefighters were able to revive the victim, an 87-year-old woman, at the scene. But she later died in the hospital.
On July 8, the suspect killed a 76-year-old woman.
He is also suspected of the murders of women aged 72 and 94, respectively, which occurred on July 15 and 24.
The motive is unclear
On Tuesday, the doctor was ordered to remain in custody pending possible charges, police and prosecutors said in a statement, according to AP.
The investigators have not specified what led to the man’s arrest or whether there is any motive behind it. The doctor is under arrest on suspicion of murder as well as one case of arson and three attempted arson.