Cops investigating the fatal Upper Street stabbing of Jonathon “JJ” McPhillips have made a new arrest.

Islington Gazette: JJ McPhillips in 2009 aged 20. Picture: JJ McPhillips familyJJ McPhillips in 2009 aged 20. Picture: JJ McPhillips family (Image: Archant)

A 23-year-old man was arrested on suspicion of murder on Friday, the Met announced this morning. He has been bailed until late next month.

Another man, who was also arrested on suspicion of murder in June, will answer bail at around the same time.

Between March and May, seven other people were arrested in connection with the February killing. They have now been released under investigation.

No one has been charged.

Dad-of-two JJ, 28, was knifed in the chest at about 12.30am on February 25 while on a night out with pals.

He had been waiting for his cousins to catch up and sat down on the Assembly Hall steps. A fight erupted nearby and a boy, 17, who JJ knew, was also stabbed – escaping serious injury. It is believed JJ intervened. He died of his injuries three days later.

Central to the investigation is an innocent bystander caught up in the melee. CCTV footage shows JJ colliding with him as he tried to flee. The suited man is seen surveying the scene as suspects, some carrying knives, run around him.

Officers are keen to speak to this man as a “significant witness”. He has never been identified. It is hoped he will see the footage and recognise himself. “His information could prove vital,” the Met said.

Det Ch Insp Dave Whellams, leading the investigation, said: “There are usually a lot of people in Upper Street at the weekend. If you witnessed the altercation on February 25 but did not realise what was happening, or felt too intimidated to contact police afterwards, we urge you to come forward.

“Every piece of information will be treated in confidence, and could prove crucial in helping us bring justice to Jonathon’s family.

“We would also appeal to friends and family of those who carried out this attack. Somebody knows who did this, and if you have the slightest indication that someone you know may have been involved, I urge you to make the police aware of your concerns.”

Anyone who saw the incident, or who has any information, is asked to call the incident room on 020 8345 3775. To give information anonymously, call Crimestoppers on 0800 555 111.