The Met is offering a reward of up to £20,000 for information leading to the location of missing man Frank McKeever.
Frank - last seen at 10pm on August 28, 2021 walking along Highbury Park - was reported missing on September 9 the same year.
The 63-year-old is from the N1 area of Islington but sometimes visited the Hackney area.
He was last seen wearing a black bomber jacket, black top, dark trousers and black shoes.
Detectives from the specialist crime team are leading the investigation due to concerns that Frank has come to serious harm.
Recently, detectives were supported by officers from the marine policing unit whose dive team searched Regents Park Canal near Shepperton Road.
To further their investigation officers have now released images of a rucksack which bears a likeness to a bag Frank often took with him which hasn’t been recovered.
Three people arrested in connection have all since been released under investigation.
On 28 September, 2021, a 30-year-old woman was arrested on suspicion of murder; on 10 October, 2021, a 46-year-old man was arrested on suspicion of murder; and on 7 December, 2021, a 45-year-old woman was arrested on suspicion of conspiracy to murder.
Detectives are also urging the public to look carefully at CCTV footage of Frank's movements in the run-up to his disappearance, released in the hopes of aiding the investigation.
Det Insp Laura Nelson, from the specialist crime command, said: "The substantial reward being offered to find Frank shows our determination to find him and answer the questions about his disappearance.
"His family are suffering hugely and we are doing all we can to provide them with support.
“I am asking the public in turn to support us and tell us anything they know that might help us discover what has happened to Frank.
"No piece of information is too small; please make contact and tell us what you know."
Frank's family are once again appealing for help to find their loved one.
In a statement, they said: "Our family had lost touch for some years but we were so happy to re-connect with him [Frank] last summer and were looking forward to being with him again to rebuild family ties.
"He seemed happy and positive about the future and he remained loyal to his favourite football team Birmingham City. We miss his cheerful and gentle personality and sense of humour."
The family - "desperate" for any news on Frank - are "very worried for his welfare and safety".
They urged anyone with information to come forward by calling 101.
Alternatively, tweet @MetCC and quote reference CAD 3224/13Nov21.
To remain anonymous, please contact Crimestoppers on 0800 555 111.
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