A former nurse wept in the dock as the court heard details of him sexually assaulting his granddaughter.
The 71-year-old man, who has permanent name suppression to protect the identity of the victim, was said to be close to the victim.
''Nobody suspected anything like this could happen,'' Judge John Macdonald told the Dunedin District Court yesterday.
The defendant's daughter was heading out of town on January 28 and left her 11-year-old girl with the man.
The grandfather touched the girl's nipples and had her touch his genitalia.
Her reaction was instantaneous.
''She immediately retreated to the bathroom,'' the judge said.
Inside, the girl wrapped herself in her mother's jersey and several towels and stayed there the rest of the night.
''That says a lot about how she was feeling at the time,'' Judge Macdonald said.
Since the incident, the court heard, the victim was withdrawn, anxious in public and had trouble sleeping.
Defence counsel Sarah Saunderson-Warner stressed her client's unblemished criminal record and spoke of his life of service which included working as a nurse.
She put the incident down to ''a number of stresses in his life'' at the time and the judge noted the defendant had been diagnosed with a mild form of post-traumatic stress disorder.
''Whether that played any part seems unclear,'' he said.
Judge Macdonald sentenced the man to seven months' home detention, which meant he was not automatically added to the Child Sex Offender Register.
Ms Saunderson-Warner pointed to a report, which classed the defendant as a low risk of reoffending, as reason not to add him to the register.
The judge, while accepting it was a finely balanced decision, concurred.
The man was also ordered to pay the victim $5000 and a protection order was granted in favour of his daughter and granddaughter.
