"We have just about had enough. My wife, Mary, is in a terrible state about it it all and we just cannot carry on," said Mr Gaudian, of Sedbury.
"This person has to be stopped. He thinks he is above the law."
Mr Gaudian's son James died in a road accident near the Sedbury turn off of the A48 five years ago, and is buried in Itton Churchyard where the two outrages occurred.
This time the memorial stone has again been covered in paint but the picture it bears, which was replaced after it was wrenched off in June, remains intact.
Other incidents have occurred over a three year reign of abuse which Mr Gaudian believes are caused by someone with a grudge against the family.
"There has been graffiti on the road signs since June, and my daughter's car windows have been broken twice," he said.
Chepstow Police are working on the case but Mr Gaudian says it appears to be hard for them to find proof to charge the culprit. Scenes of crime officers have examined the memorial following the latest attack last weekend.
"It is getting so that we really don't know what to do. I sometimes feel so angry about it I think of taking the matter into my own hands," said Mr Gaudian, whose wife has had hospital treatment through worrying about the campaign of spite.
"We just want it to stop. It probably won't stop until he is behind bars."
Chepstow police said they were looking into the matter and Inspector Stan Jones said it was very disturbing.
"It is very concerning for me. It is hard to believe anyone could do something as despicable as this," he said.
"Mr Gaudian and his family must feel dreadful and I have every sympathy for his plight. At the moment my officers are looking into it and I can say nothing further at this stage."