“A really quite twisted test on the effects of maternal deprivation, conducted just a few miles across the border,” Marini explained. “Wallner got the idea from a study conducted by René Spitz. But he went much further.”

“What did he do?” asked De Carli.

“He was the director of an institute that looked after orphans. He ordered the nursery staff who took care of the infants to withhold any kind of maternal care from their charges. The children weren’t referred to by name, but only by the number attached to their cots. This was known as ‘de-personalization.’”

“Is that even legal?” said Parisi.

“Definitely not,” Marini replied. “But Wallner and his collaborators didn’t mind. The nurses weren’t allowed to speak to the children or even to make eye contact. They wore a hood with two holes for their eyes so their facial expressions wouldn’t be visible.”

Everyone held their breaths for a moment. All eyes were on the hood now.

“The infants were fed and washed regularly, but deprived of any other form of care,” Marini went on. “Soon they began to exhibit the first symptoms of this ‘treatment’: insomnia, rejection of physical contact, wasting away, delayed development of motor functions, and an absence of facial expressions. All except one: the child in cot number thirty-nine. This infant stayed alert and did not waste away. On the contrary, he continued to grow. Wallner thought he had found in him the ‘Father’ as theorized by Freud: a natural leader equipped with an extraordinary inner strength.”

“What became of the children?” De Carli asked.

Marini scrolled down to the end of the webpage he was reading from.

“A nurse who had recently been hired told the authorities about Wallner, and the police stormed the institute. The children were rescued and within months their symptoms began to fade until they disappeared altogether. But Wallner managed to get away, and he took with him the child from cot number thirty-nine, his greatest discovery.”

“What was the child’s name? Does it say?” Teresa asked, trying to control the tremor in her voice.

“Andreas Hoffman. Wallner and the child were never found. Agnes Braun, Wallner’s closest collaborator, was put on trial and sentenced to twenty years in prison. When the institute opened again, Magdalena Hoos, the young woman who had alerted the authorities, was hired to work there again. The police later learned that Wallner had been obsessed with Nazi theories of eugenics.”

Andreas. Teresa finally felt she had a connection with him.

“Poor kid. I wonder what happened to him,” said De Carli. Marini swore and Knauss looked down at his trousers, picking at them compulsively.

Teresa regained her composure and looked at them all incredulously.

“Don’t you see?” she said. “It’s him. The child who disappeared is our killer.”

She got to her feet, her agitation making her forget her aches.