The doctor who led the session has acknowledged giving the participants various substances and drugs during the meeting, Martin Steltner, a spokesman for the Berlin prosecutor's office, told The Associated Press on Sunday. It was not clear whether illegal drugs were given and whether the substances were injected or taken orally.
A police statement said autopsies have been carried out on the two dead people but "the chemical-toxicological investigation will take a while."
Police said the session took place in a house and medical practice in the leafy Hermsdorf neighborhood in the north of Berlin. The 50-year-old doctor who worked there was detained and a homicide division was investigating the case, police said.
The doctor, his 41-year-old wife, who runs a practice for alternative medicine in the same building, and 12 other people attended the session Saturday, according to a police statement.
"During the session, which lasted several hours, he supposedly gave the patients various kinds of substances and drugs that initially led to reactions like nausea and vomiting," the statement said.
When the symptoms got worse, one of the participants called emergency services, according to the statement.
When police and ambulance cars arrived at the practice, they found twelve people who appeared to have been severely poisoned, it said.
A 59-year-old man died at the scene and a 28-year-old man died that night in the hospital, police said.
On Sunday afternoon, nine other people were released from the hospital. One patient was still in critical condition.
On the Internet, the doctor identifies himself as a psychotherapist for individuals and groups. He specializes in "depth psychology, bodywork and art therapy, and spiritual crises," according to the Web site.
By Associated Press Writer Andrea Backhaus