A couple allegedly lied to a 13-year-old boy in their care, telling him had seven brain tumours and was going to die, in order to earn money from donations.

Ginny Irovando Long and Robert Edward Long, from Fort Walton Beach, Florida, were arrested on Thursday (1 February) and charged with nine counts of fraud and one count of child abuse.

Investigators allege that the couple appealed for donations to cover the cost of his "medical expenses", Okaloosa County Sheriff's investigators wrote in a news release.

The pair, of Scottwood Drive, allegedly set up a T-shirt fundraiser for the boy at his school to pay for his medical and funeral expenses.

Police say they also shared the false cancer diagnosis on their Facebook pages, and created a GoFundMe account to raise money for his care.

Prosecutors believe the boy was living in fear for at least eight months, believing he had terminal cancer after he was told of the bogus diagnosis in May 2017.

"The 13-year-old has spent the last eight months believing he is going to die from brain cancer, but the OCSO's investigation revealed his medical records prove no brain tumours exist," officials said.

34-year-old Ginny Irovando Long claimed it was a miracle the boy had lived three days past Christmas and "the only person that knows when he is supposed to go is God," reported My Panhandle.

But investigators noticed that the boy appeared well in photographs and they questioned him last November after a school resource officer alerted authorities that the couple was potentially exploiting the boy.

The boy told police that his diagnosis scared him and he did not like to talk about it, reported the Northwest Florida Daily News.

An arrest report revealed that Ginny Irovando Long initially told officers the boy had seven brain tumours and if he did have surgery, he could turn out to be a "vegetable".

But she could not prove that he had any tumours and the boy's physician told investigators that he did not have cancer of any sort, say police.

Robert Edward Long, 47, said he had assisted the woman with fundraisers, according to reports.