A Texas judge has blocked the execution of the first man to be put on death row in the US for murder charges related to “shaken baby syndrome”, less than two hours before the capital punishment was due to be carried out.

Robert Roberson, 57, was sentenced to death in 2003 for the death of his two-year-old daughter, Nikki Curtis, after a post-mortem examination concluded she died of injuries from abuse.

Roberson and his lawyers have long maintained the child died of complications from pneumonia.

Roberson’s lawyers have also argued that his autism - which was undiagnosed at the time of Nikki’s death - was used against him after police and medical staff became suspicious at the lack of emotion he displayed.

Autism can affect how a person communicates with others.