A schoolgirl is accused of stabbing her three-year-old half-brother to death before writing “this is your son” on the wall in his blood in a sick message to their mother.

The girl, a 15-year-old known only as Olivia, allegedly stabbed her little brother Nicolas 28 times as he slept at their home in Detmold, Germany.

The teenager had reportedly been babysitting the youngster. She allegedly wrote the chilling message: “Here is your son,” on the wall for her horrified mother, 46-year-old Agnieszka, before fleeing.

Cops caught up with her six miles from her home after launching a helicopter search. The schoolgirl faces ten years of youth detention if convicted of killing little Nicolas, also known as Nico.

The 15-year-old girl yesterday went on trial in Germany for killing her 3-year-old half-brother, with prosecutors saying she stabbed him 28 times in November with a knife as he was sleeping.

The case had horrified people across Germany in 2019. A key question in the trial is why the girl acted as she did.

“My client wants to know this too and thus cooperated with the psychiatric expert,’’ defence lawyer Helmut Woehler told dpa on Monday.

The court proceedings are taking place behind closed doors because she is a minor.

The killing allegedly took place in the family flat in the north-western town of Detmold, the parents were not home at the time.

Relatives found the body of the boy and notified the police, the girl was found the next day some 9 km away, in the town of Lemgo.

She did not resist arrest and was calm at the time, according to prosecutors. She is believed to have spent the night outdoors and walked to the neighbouring town on dirt roads.

The girl identified herself as the perpetrator after her arrest but said she was suffering from memory loss.

The psychiatric expert is among the about 20 witnesses expected to testify at the trial.

He has been asked to comment on the defendant’s developmental stage and her criminal responsibility.

She faces up to 10 years in jail if she is found guilty of murder.

The girl continues to be rather introverted, but has become used to life in jail and is attending school there, Woehler said.

The court has scheduled three further trial dates this month.