A mentally-ill young man stabbed new dad Dr Jeroen Ensink to death as he went to post baby cards announcing the birth.
His daughter, Fleur, had arrived into the world just 11 days before the tragedy.
The 41-year-old academic was renowned in his field and died metres from the front door of his London home on December 29 last year.
Femi Nandap, 23, had launched a random, vicious attack, repeatedly stabbing Dr Ensink.
Jeroen's wife, Nadja, was at home with their baby. She became concerned at his delay and went outside to see if she could see him. There, she found his body among Fleur's baby cards, which were strewn on the ground and splattered in blood.
Her husband was pronounced dead at the scene.
This morning at the Old Bailey, Nandap, of Woolwich, south-east London, admitted the manslaughter of Dr Ensink by reason of diminished responsibility. He appeared via video link from Broadmoor hospital.
The case has been adjourned until October 10 for sentencing.
Prosecutor Duncan Atkinson QC told the court: "There has been extensive psychiatric consideration in this case and the psychiatric opinion is clear, cogent and unanimous."
He added: "Given the defendant's history, the facts of the offence itself, the Crown take the view it is not in the public interest to pursue the murder allegation and that decision has been taken I'm consultation with the family of the deceased."
Less than three months before he killed Jeroen, who was originally from Holland, Nandap appeared in court accused of possessing a knife and assaulting a police officer.
It was alleged he had two kitchen knives with him in Edmonton on May 22, 2015 and that he assaulted PC Wellings on the same day.
Dr Ensink was a renowned water engineer and a dedicated humanitarian who was committed to improving access to water and sanitation in deprived countries.
