One of the bodies showed clear indications of external trauma that could direct the course of the investigation. Those injuries were also likely the cause of death, prosecutor Johannes Daheim told reporters in the city of Olpe on Wednesday. The babies did not freeze to death, Daheim said.
Daheim said police did not want to release more information until the 44-year-old mother of the children could be questioned. She was put under psychiatric supervision after being taken into custody on Sunday and remains unfit for questioning, he said.
Two of the woman's grown children found the three babies' bodies wrapped in plastic bags underneath a stack of expired food in the basement freezer of the family's rural home in Wenden, a town in the German state of North Rhine-Westphalia.
The first baby autopsied on Tuesday showed no signs of violence, Daheim said. All three babies were born alive and without disabilities; one baby was slightly premature. Investigators are conducting genetic tests in coming days to confirm the woman's 47-year-old husband was the father, police president Diethard Jungermann said.
Family and neighbors have said they had no idea the woman, who is overweight, was pregnant. The case is the latest in a series of grisly infanticides that have shocked Germany.
Sentence in other infanticide case
Another such incident came to an end on Wednesday, when a German court jailed a mother for nine months for manslaughter in the deaths of three newborn babies.
The court in the eastern city of Erfurt said the now 22-year-old woman gave birth to two healthy girls and a boy in 2002, 2004 and 2005 and then left them to die.
The defendant, whose name was not released by the court, had testified that the children were stillborn.
Defence attorneys pleaded for a suspended sentence of two years while state prosecutors called for a 10-year jail term.
The decomposed corpses of the three newborns were discovered in January 2007 at a property once belonging the defendant's parents in the town of Thoerey.
The new owners of the property found the remains packed away in plastic bags and cardboard boxes in a garage.
In the most notorious case of child deaths in Germany in recent years, a woman was sentenced to 15 years in prison in 2006 for manslaughter of eight of her babies.
She had hid their remains in buckets and flower pots as well as in an old fish tank at her parents' home.
Last November, a 35-year-old woman from Erfurt was sentenced to 12 years in jail for killing two of her babies and hiding their bodies in a freezer.
In December 2007, a woman was arrested after police found the bodies of five children aged between three and nine years in a house in Darry, near the northern city of Kiel.
The same week a woman was arrested in Plauen in eastern Germany on suspicion of killing three newborn babies she had borne. The infants were discovered in a trunk in the cellar, on the balcony and in a refrigerator.
Last Saturday, a dead baby was found in a ditch in the eastern state of Saxony.
The cases have prompted many hospitals to install so-called 'Babyklappen,' hatches for mothers to anonymously deposit infants for care when they believe they are unable to raise them themselves.