Detectives hope the photo of the note and CCTV images of the man will help trace the offender after the raid on the NatWest bank in Bolton Road, Irlams O' Th' Height, Salford, on December 11 last year.
No weapon was seen but an amount of cash was handed over before the suspect fled.
Detective Chief Inspector Ben Ewart, of Greater Manchester Police (GMP), said: "Since this brazen robbery we have conducted numerous inquiries to try and identify the suspect.
"We are determined that the person responsible for this crime is brought to justice and I am now appealing to the public for help.
"While no weapons were seen, the offender has robbed a bank and in the process - through the medium of the written word - threatened to shoot staff if they did not comply."
Some of the cash was recovered nearby after the offender activated a security dye pack.
He is described as white, between 5ft 10in and 6ft, of slim/athletic build, in his late 20s or early 30s, with a sallow complexion, pock marks on his cheeks and slight stubble.
Anyone with information is asked to call Swinton CID on 0161 856 5351, or Crimestoppers, anonymously, on 0800 555 111.
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