sandy hook
Grace McDonnell was one of 20 children killed during the sandy Hook shooting Where Angels Play Foundation

A memorial dedicated to one of the children killed during the Sandy Hook massacre has been stolen by a man who claims the shooting never occurred.

A sign at the Grace McDonnell playground in Mystic, Connecticut was stolen by a Sandy Hook 'truther', who then rang the mother of the seven-year-old to explain he took the sign because he believes the Newton tragedy was a hoax.

The sign featured a peace symbol which was drawn by Grace, who was one of 26 people, including 20 children, killed by Adam Lanza during the shooting spree in December 2012.

Grace's mother, Lynn McDonnell, narrated how a man told her why he took the sign and said her daughter "never existed", according to CBS2.com.

Sandy Hook 'truthers' are conspiracy theorists who believe the Newtown shooting was a hoax as part of a ploy by the government to implement stricter gun control laws in the US. By suggesting McDonnell's daughter never existed, the man who stole the sign is suggesting she and her daughter are also part of the alleged conspiracy.

The Grace McDonnell playground is one of 26 currently being built in New York and New Jersey by the Where Angels Play Foundation to honour the victims of the massacre.

The foundation said they have ordered a replacement sign. The incident occurred less than a week after a playground dedicated to fellow Newton victim Ana Grace Marquez-Greene was vandalised in Hartford, Connecticut.

The sign was found spray-painted with the words "Peace 2 Sandy Hook" with a peace sign replacing the first word.

Police are investigating the incident, but Ana's mother, Nelba Marquez Greene, said she was not upset at the graffiti and hopes to install a board at the playground so others can leave similar messages of condolences.