Alan Lewis is raising money by running from one coast of Northern Ireland to the other after his son Oliver lost both his legs below the knee to Meningitis last year.
But it has come to light that a conman is working to hijack Alan's efforts and rob people who believe they are donating money to the local dad's fundraiser.
He has been concentrating in the Lurgan and Banbridge area, contacting local businesses for sponsorship, using a fake sponsor form.
However none of the money he has collected has made its way to the Meningitis Trust.
Mr Lewis explained how he came into contact with this man, "He was in Banbridge three weeks ago, and came to my business raising money for a different charity. He had identification and I gave him a fiver.
"I told him about the work I was doing and he said he would take part, but thought nothing more of it.
"Two Fridays ago I heard from a work colleague who said a man with short, cropped ginger hair and an English accent said he was running with me and was raising money for the event.
"He had four pages of filled sponsor forms. It's a joke, he is obviously conning people.
"I have been in touch with the PSNI but he seems to have moved on, I would very much like to find this guy."
Businesses and members of the public are being urged to be vigilant.
Anyone who is legitimately collecting on behalf of the Meningitis Trust will have ID badges, correct documentation and when collecting with a tin or bucket, fully sealed containers.
Anyone with information can call Anne Currie at the Meningitis Trust on 0845 120 2123.