A memorial service is to be held in Leeds on Sunday to mark the second anniversary of what police describe as a "cold-blooded murder".
Pat Regan has set up a Leeds branch of Mothers Against Guns
Danny Regan, 25, was found shot dead at his home in Station Road, Haydock on Sunday 15 December, 2002.
He was originally from Leeds but had lived in Haydock for 12 months before his death. His killer has not been found and police are asking for help.
His mother Pat, of Leeds, said she misses him more than ever.
Police believe a gunman got into Mr Regan's house on 12 December, 2002, armed with either a semi-automatic or pump-action shotgun.
Since the incident Mrs Regan has campaigned against gun-crime and set up a Leeds branch of Mothers Against Guns.
She said: "It's still so hard to face the idea that my son is never coming home and all of our family miss him terribly."
The service at All Hallows Church, Regent Terrace, Hyde Park begins at 1800 GMT and will remember all those lost to gun crime.
Mrs Regan also appealed for anyone who could help police solve his murder to come forward.
"Please think or our family, of Danny's children, and help us begin to find some sort of peace with his death," she said.
Det Supt Julieanne Wallace-Jones of Merseyside Police said: "Our commitment to tracing those who murdered Danny remains undiminished and I would appeal to anyone who might not have already come forward with information to contact us."