Autopsies on the bodies of five brothers believed to have been slain by their mother were performed on Thursday.
The bodies of the boys, aged 3 to 9, were found in their home on Wednesday after their 31-year-old mother told a doctor where to find them, prosecutor Uwe Wick said.
It is believed that they were killed either on Tuesday or on Wednesday, he said.
German news media have reported that the children were doped with pills and then suffocated with plastic bags, but Wick would not comment on the cause of death.
Three of the children were fathered by one man, while two were fathered by another. Neither man lived with the family in the tiny village of Darry, in the northern German state of Schleswig-Holstein, prosecutors said.
The autopsies, being done in Kiel, would provide more details as to the time and cause of death, Wick said. It was not known when the results would be ready.
The mother, whose name has not been released, was ordered held in psychiatric care after the grisly discovery and was to go before a judge Thursday for a ruling on a request by authorities that she be held during the investigation.
First indications are that mental illness is a possible motive in the slayings, Wick said.
"We have requested the woman be held in a secure psychiatric facility because we assume that she represents a general danger to the public," he said.
The discovery of the dead brothers on Wednesday afternoon came the same day that authorities in eastern Germany announced they had found the bodies of three infant girls and had taken their mother into custody on manslaughter charges.
The first body was found Nov. 27 in the eastern city of Plauen, near the Czech border, after authorities asked why the child, born in a clinic in 2002, had not yet been brought for a required checkup before starting school. The body of the baby girl was found wrapped in plastic and hidden in a suitcase in a storage area of a relative's home, police said.
The two other bodies of baby girls were found Tuesday in the woman's home, police said. They were also found wrapped in plastic, one in a freezer and the other on her balcony.
The 28-year-old mother, who was not identified by name, was taken into custody. Her two surviving children - a baby and a child in grade school - were taken into protective custody.
The woman has denied killing the three babies.