A catalogue of missed opportunities from the authorities allowed a mentally ill man to stab a much-loved academic on his way to post cards.

Femi Nandap, 23, has pleaded guilty to knifing Dr Jeroen Ensink, 41, who suffered catastrophic injuries after he was repeatedly stabbed in the back outside his Islington home on December 29 last year.

Today, it emerged the academic's killer was caught with two kitchen knives after assaulting a policeman but the case was dropped because the Crown Prosecution Service (CPS) claimed they did not have enough evidence to prosecute him.

Guilty: Femi Nandap, 23, left, has admitted the killing of Dr Jeroen Ensink, 41, pictured, who was repeatedly stabbed in the back outside his Islington home

Family: Dr Ensink's wife holds the couple's daughter Fleur - who was 11 days old when her father died

Tragedy: Dr Ensink was off to post cards to tell loved ones about the birth of his beloved daughter Fleur

Nandap, of Woolwich, south east London, was arrested in May last year and charged with wielding knives in public and assaulting a police officer.

He later flew back to Nigeria in June for three months, missing his bail appointment in August.

He finally appeared in court in October, but was granted bail by magistrates - despite objections from the prosecutor.

The prosecutor at Highbury Corner Magistrates' Court on October 12 objected to Nandap being granted bail after he previously failed to surrender.

But bail was still granted following representations from the defence.

The CPS dropped the knife and assault charges on December 23 after deciding their was 'insufficient evidence' to obtain a conviction.

Six days later he stabbed Dr Ensink to death in the street.

Dr Ensink was killed 11 days after he became a father for the first time and he had gone out to post new baby cards to inform friends and family of the arrival of his daughter Fleur.

Much-loved: Dr Ensink had just had his first child with wife Nadja Ensink Teich, who walked outside to find her husband fatally injured

Nandap approached Dr Ensink in the street and straddled him while stabbing him repeatedly and when witnesses rushed to protect him the killer stood nearby still clutching a large kitchen knife.

The new baby cards were strewn on the pavement around him and splattered with the much-loved academic's blood.

Nandap had launched his ferocious random attack while Dr Ensink's wife Nadja was at home with the baby awaiting his return.

When he failed to arrive, she went outside to find police had cordoned off the street and the cards her husband had been carrying strewn on the pavement splattered in blood.

HOW CPS DUMPED KILLER'S CASE EVEN THOUGH HE HAD TWO KNIVES AND HIT A PC The academic's killer was caught with two kitchen knives after assaulting a policeman but the case was dropped because the CPS claimed they did not have enough evidence to prosecute him. Nandap, of Woolwich, south east London, was arrested in May last year and charged with wielding knives in public and assaulting a police officer. Nandap later flew back to Nigeria in June for three months, missing his bail appointment in August. He finally appeared in court in October, but was granted bail by magistrates - despite objections from the prosecutor. The prosecutor at Highbury Corner Magistrates' Court on October 12 objected to Nandap being granted bail after he previously failed to surrender. But bail was still granted following representations from the defence. The CPS dropped the knife and assault charges on December 23 after deciding their was 'insufficient evidence' to obtain a conviction. Six days later he stabbed Dr Ensink to death in the street. Advertisement

Friends said he had been overjoyed to have become a father and had 'doted' on his child.

Detective Chief Inspector Jamie Piscopo, of the Met's Homicide and Major Crime Command, said: 'Dr Jeroen Ensink left his home that lunchtime to post a number of cards to friends and family to inform them of the recent birth of his daughter. What should have been the happiest time of Jeroen's life was ended by the violent and unprovoked actions of Nandap.

'Jeroen had only walked a short distance when he was approached by Nandap, who launched into a vicious attack with a knife. He did not stand a chance, and now, sadly, his daughter will grow up without her father in her life.'

It can revealed today that the killer had knife and assault charges against a policeman dropped just days before the fatal stabbing.

At an earlier hearing now retired Judge Charles Wide QC demanded prosecutors find out why and said: 'I imagine a judge might be concerned about the discontinuance of three charges in the five days before this incident.'

'I've no idea of the circumstances, but I could see there may be some public concern about that.'

The Crown Prosecution Service said today it dropped Nandap's knife and police assault charges because of a 'lack of evidence' - but said even if he was prosecuted he would still be free on bail.

A spokesman said: 'This was a tragic case and our sympathies are with Mr Ensink's family.

'The case against Timchang Nandap was discontinued on 23 December following a review that determined there was insufficient evidence to provide a realistic prospect of conviction.

'Even if the case had proceeded, the bail conditions he was subject to until his scheduled trial would not have prevented him being at the location of the incident on December 29 2015.'

Julian Hendy, of charity Hundredfamilies, said: 'This is another deeply distressing case of an innocent man and young family destroyed by the violent actions of a seriously mentally ill offender.

'These cases are happening now far too often and we await with interest the results of the psychiatric investigations to see if there were opportunities that could have prevented this terrible tragedy.'

Dr Ensink, who is originally from the Netherlands, was a lecturer in public health at the London university since 2008.

He was an expert in sanitation and water management, and worked in developing countries including Ethiopia, Senegal, Vietnam, Afghanistan, and Sri Lanka.

Scene: Police standing guard near Dr Ensink's home in Holloway after he was killed by the mentally ill knifeman

The lecturer had just become a father and was working on a study in the Democratic Republic of Congo to help prevent cholera at the time of his death.

The 41-year-old, a biologist, suffered multiple stab wounds after being attacked at around 1.50pm.

Nandap, of Pett Street, Woolwich, southeast London, denied murder but pleaded guilty to manslaughter by reason of diminished responsibility.

Court records show he was at Highbury Corner Magistrates' court on 12 October last year accused of possession of a knife and assaulting a police officer.

It was alleged he had two kitchen knives with him in Primrose Gardens, Edmonton, on May 22, 2015, and that he assaulted PC Wellings on the same day.

Prosecutor Duncan Atkinson QC said Nandap had skipped bail on the previous matters when he was allowed to fly to Nigeria, returning in October instead of August as agreed. But the court heard he was not prosecuted for a bail offence.

Shocking: Nandap had skipped bail on the previous matters when he was allowed to fly to Nigeria, returning in October instead of August as agreed. But the court heard he was not prosecuted for a bail offence.

But when the charges were dropped he knifed Dr Ensink in an apparently motiveless attack.

At a brief hearing at the Old Bailey on Thursday, Nandap, of Woolwich, south-east London, admitted the manslaughter of Dr Ensink by reason of diminished responsibility and the case was adjourned until October 10 for sentencing.

Dr Ensink, originally from Holland, was a renowned water engineer and a dedicated humanitarian who was committed to improving access to water and sanitation in deprived countries.

At the time of the killing, Professor Peter Piot, director of the London School of Hygiene and Tropical Medicine, said: 'Dr Ensink joined the school almost a decade ago, and at the time of his death he was leading a large study in the Democratic Republic of Congo to understand how improvements in water supply could control and prevent cholera outbreaks.'

A memorial fund set up in the wake of Dr Ensink's killing has raised more than £20,000, with donations from friends and former students alike.

Lauren D'Mello-Guyett wrote: 'Always in my thoughts! Jeroen was a great friend, mentor, laugher (sic) and could always make you feel great. I owe so much to him and his guidance. Remembered and never forgotten.'

Dorica Boyee's message stated: 'Jeroen was a blessing to this world. May his light continue to shine through his legacy.'