A widow is expected to speak out at the sentencing of a mentally ill man from Woolwich who stabbed her husband to death just days after walking free from court.

Renowned academic Dr Jeroen Ensink, 41, was attacked by Femi Nandap as he left his flat in Islington, north London, on December 29 last year.

The proud new father had been on his way to post cards announcing the birth of his daughter Fleur, 11 days before.

Dr Ensink's wife Nadja was at home with the baby and when he failed to return went outside to find the road cordoned off.

The cards her husband had been carrying were strewn on the pavement stained with his blood.

Six days before the killing, Nandap, 23, had charges of having a knife and assaulting a police officer dropped in court due to "insufficient evidence".

He had also breached his earlier bail conditions by going to Nigeria, raising the question of why he was not also prosecuted for that.

At an earlier hearing, Nandap pleaded guilty to Dr Ensink's manslaughter by diminished responsibility.

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Nadja Ensink with her husband Dr Jeroen Ensink. Picture: PA WIRE.

Prosecutor Duncan Atkinson QC said the defendant, who is being held at Broadmoor secure hospital, had suffered an "abnormality of mental function at that time".

Mrs Ensink-Teich, who has moved back to her native Holland, will attend the Old Bailey sentencing with her baby daughter.

She is expected to read a victim impact statement ahead of the sentencing by Judge Nicholas Hilliard QC.

Nandap is expected to receive either a hospital order or a hybrid order by which he will be held in a psychiatric unit with the option of later being transferred to prison.

Dr Ensink, who worked at the London School of Hygiene and Tropical Medicine, was a renowned water engineer and a dedicated humanitarian committed to improving access to water and sanitation in deprived countries.