Why did the blue-eyed woman with long black hair blow herself up and kill two others at midnight mass?

A Christmas Eve service in a Frankfurt church ended in carnage when a woman blew herself up, killing herself and two of the congregation. German police issued a photograph yesterday of the severed head of a woman, with blue eyes and long black hair, believed to be responsible for the attack. She appears to have left no note.

Yesterday, as investigators sifted through the church and heard the testimonies of shocked witnesses, the only clue was a mis-shapen torso and the unknown head blasted clear of the body. What lay inside that head to ordain the extinction of three lives may never be known.

The suspect, aged about 30, was thought to have detonated two hand-grenades strapped to her body, just as the Lutheran congregation began to sign the first hymn during the late-night service. Two sisters, aged 59 and 61, who were sitting near her, died instantly. Thirteen people were injured, including a mother and her 12-year-old daughter, who were in critical condition in hospital last night.

Investigators were confident that the attack was not linked to terrorism or politics. "The evidence indicates that she was disturbed and wanted to kill herself in a spectacular action," said a police spokesman.

The suspect entered the small church in the working class suburb of Sindlingen, shortly after the pastor opened the service at 11pm. She sat in the third pew from the back, and although it was warm inside, she did not remove her coat. Witnesses recall seeing her sitting still, with her face shrouded by a scarf, her eyes apparently fixed on the Christmas tree next to the pulpit.

The grenades went off as the 70-strong congregation rose to sing, 15 minutes into the service. Worshippers at the front of the church recalled hearing a muffled bang behind them. By the time they had swung around, the orderly rows in the back had become unrecognisable. Crumpled blue hymn sheets littered the floor. The pews had been reduced to splinters, covered with broken bodies. The red carpet in the aisle was torn up, with blood-soaked garments lying scattered in the middle. A pair of twisted spectacles had been propelled across the hall. And the white walls were splattered with charred human remains.

The worshippers, mostly local people who knew each other well, fled in panic from the church, only to run back, fearing that the attack had come from outside.

"At this point we can only speculate about the cause of this criminal act," said Manfred Feist, the city's police spokesman. "The evidence indicates that she was disturbed and wanted to kill herself in a spectacular action."

Frankfurt's police chief, Wolfhard Hoffmann, said: "I have no idea who could have done such a thing on a day like this. We are completely baffled."

n A baby boy born on Christmas Eve froze to death while his homeless mother wandered through the German city of Goettingen looking for a warm place to stay, police said yesterday.

Wrapped in a blanket, the boy was cold and lifeless when his 28-year- old mother finally reached a homeless shelter to escape the icy night, a spokesman said.

She had given birth only hours earlier in a deserted house in the university city and the boy at first seemed healthy, she told police.

A doctor who hurried to the shelter could only pronounce the infant dead and determine there were no signs of any violence on the corpse, the spokesman said.