“This case is tragic … the whole event, in my view, so unnecessary,” she said.
“The law cannot remedy or heal this degree of suffering.”
Mrs Rigby had been on her way to collect her now-deceased son for a Sunday morning church service and family gathering.
The court heard Murray was speeding at up to 103 km/h in a 60km/h zone when he lost control while attempting to overtake another vehicle by passing through a narrow gap in traffic.
His BMW became momentarily airborne as it crossed over a median strip into the other lane, colliding with Mrs Rigby’s Holden before mounting the kerb and hitting a brick fence in front of a house.
Judge Braddock said Mrs Rigby’s death had been devastating for her son, who had Down syndrome and early-onset dementia.
“He would have been inconsolable,” she said, noting that it had also been tragic for Mrs Rigby’s three surviving children.
The judge rejected Murray’s claim that the crash had been caused by mechanical failure, saying it was clear he had already been driving dangerously and the impact of the car striking the kerb had been the likely cause of damage.
Murray appealed through his lawyer for a suspended sentence on the basis that he was the primary carer for his now-disabled son.
While noting the father-of-two had a previously clean record, had shown genuine remorse and had suffered as a result of the crash, Judge Braddock said the seriousness of the offending meant a prison term was the only appropriate sentence.