Police investigating the fatal stabbing of Daniel Frederick on the Milton Gardens Estate have released CCTV footage of two people they want to track down.

Daniel, 34, was attacked just before 5.50pm on January 8 after attending a hospital check-up for his pregnant partner. He was yards from his front door in Shakspeare Walk, Stoke Newington.

Det Insp Paul Considine, who is leading the investigation, believes Daniel was mistaken for somebody else, and was a “completely innocent victim”.

He told the Gazette on Friday there was no evidence to link Daniel’s death with another attack two days later in Lordship Road in which a man was stabbed and shots were fired, though he has not ruled out a connection.

Police also say there is no evidence to suggest a link between Daniel’s killing and the fatal stabbing of a 26-year-old man on Stoke Newington’s George Downing Estate on Sunday night.

Det Insp Considine is appealing for help in tracking down two people seen walking along Clissold Road towards Clissold Park after Daniel was stabbed.

He believes one of the men could have been caught up in the attack and also been knifed.

He said: “I have released these images in a bid to jog the memory of anyone who might have seen these men or know them – please contact us urgently.

“I believe one of the two men, the one in the darker jacket, may well have sustained an injury to his right leg during the attack which might be consistent with a stab wound.

“We are also still appealing for any witnesses or anyone with information who has not yet spoken to us to come forward.”

Daniel, who worked doing hotel security work, went to St Matthias Primary School and then Highbury Grove, and was a big Arsenal supporter. He had three children, aged eight, six and one, with another on the way.

Four arrests have been made so far over his death.

A 26-year-old man arrested on suspicion of murder has been released under investigation and a boy, 16, has been bailed until mid-February over the same offence.

Police arrested an 18-year-old man yesterday in Essex on suspicion of murder and he has been brought in for questioning in east London. A 41-year-old woman was arrested at the same time on suspicion of assisting an offender.

Det Insp Considine told the Gazette he was not sure whether Daniel was targeted for being in an opposing gang’s territory or if it was purely a case of mistaken identity.

And on a possible link to the Lordship Road incident, he said: “We haven’t ruled out a link but there is nothing at the moment to say it’s definitely linked. We are pursuing several leads.”

Anyone with information can contact the incident room on 020 8345 3734 or Tweet information to @MetCC.

Alternatively, you can contact Crimestoppers anonymously on 0800 555 111 or at crimestoppers-uk.org.