It was one day in August last year that the man was sitting on a bench in a square in Uppsala when the girl and her friends came by.
They started talking and then the man sexually assaulted the girl.
The girl immediately told a relative, who made sure that an adult followed the man and that he was later arrested.
The 90-year-old man himself has denied the crime and claimed that he only put one hand on the girl.
But the district court finds the girl's story very credible and the man is convicted of sexual assault against children.
Age comes into play
Tinsgrätten is considering in the sentence whether he should avoid prison due to his advanced age, but thinks that the crime is too serious for him to avoid it.
However, his age comes into play when the sentence is set at one month.
He will pay damages to the girl of almost 30,000 kronor.