Immediately afterwards, Marsden turned towards the victim and, without warning, punched him once on the side of the face. It was a full force blow which knocked the officer off his feet and rendered him unconscious, the summary said.
After the officer staggered to his feet, he helped his two colleagues lock the defendant in his cell.
The victim had a swollen left cheek, swelling and a cut to his inside upper lip, a stiff neck and a sore shoulder, lower back and hip.
Marsden admitted a Crimes Act assault and was sentenced to six months' jail, the term to be cumulative on his existing sentence.
Judge Michael Crosbie said the defendant was fortunate to be charged with a Crimes Act assault which carried a one-year maximum.
Given the circumstances, the Crown could have proceeded on a far more serious charge.
The increase in the number of assaults on prison officers was a matter of concern, the judge said.
A clear message was needed that those who assaulted Corrections officers would be dealt with severely.
Prison was "not a two-way street". Those who were in prison were expected to comply and prison officers should receive the full support of the law in carrying out their duties, Judge Crosbie said.