Flowers and candles lay near the track where an 8-year-old boy was pushed on the rails and died at the train station in Frankfurt, Germany, on Monday. Photo: AP Photo/Michael Probst

Frankfurt – The 40-year-old man suspected of pushing an 8-year-old boy and his mother in front of a train in Frankfurt refused again to give a statement on his motivation for the crime.

"He hasn't said anything about a possible motive or why he came to Frankfurt," a spokeswoman for the prosecution said on Wednesday. The man had also remained silent during previous questioning.

The Eritrean national was formally arrested on Tuesday and is facing one murder charge and two attempted murder charges after he was seen pushing an 8-year-old boy and his mother off a platform at Frankfurt central train station and onto the train tracks on Monday.

The 40-year-old woman was able to save herself and avoid the oncoming high-speed train, but her son suffered fatal injuries.

A third person, a 78-year-old woman, was also pushed but managed to avoid falling off the platform. German law enforcement authorities said the man did not know the victims.

The man lives with his wife and three children in Switzerland. His family have received hateful comments and attacks online, Swiss police said, adding that they may open an investigation.

They did not comment on media reports claiming that the family had left their home and been taken to a safe location.

Until recently, the suspect was considered to be well-integrated, and had been touted as an example of successful integration by Swiss authorities.

His employer is quoted in a report about refugees in 2017 as saying that he had "made a good impression from the beginning" and that he was "active and reliable" at his job at Zurich's public transport company.