MORE than 70 years after a 14-year-old black boy went to the electric chair for the killings of two white girls, a US judge quashed his conviction on Wednesday.

George Stinney was arrested, convicted of murder at a one-day trial and executed in 1944 over the deaths of 11-year-old Betty June Binnicker and seven-year-old Mary Emma Thames.

The whole case spanned only about three months and there was no appeal. 

The speed at which the state had meted out "justice" against the youngest person executed in the US during the 20th century had been shocking and extremely unfair, Circuit Judge Carmen Mullen wrote in her ruling on Wednesday.

Investigators had arrested George, claiming that witnesses had seen him with the girls as they picked flowers. 

The girls had both been beaten badly about the head with an iron railroad spike. A search found their bodies several hours later.

George was kept away from his parents and authorities later claimed that he confessed.

But his supporters said that he was a small, frail boy so scared that he had said whatever he thought would make the authorities happy. 

There was never any physical evidence linking him to the deaths. 

During a two-day hearing in January, Judge Mullen heard from George’s surviving brother and sisters, people involved with the trial and experts who questioned the autopsy findings and the confession.

It took Judge Mullen nearly four times as long to issue her ruling as it took in 1944 to go from arrest to execution.