The Sør-Trøndelag District Court ruled that the 50-something man carried out the attack while asleep and thus couldn't be held accountable.
The case dates back to a 2014 incident in which the man slept in the same bed as his 14-year-old granddaughter. The girl awoke to find her grandfather touching her lower body and then rushed into the bathroom where she called a friend who reported the incident to the police.
When officers arrived, they were able to gather evidence including the grandfather's DNA on the girl's underwear and genitals.
The man insisted that he must have done it in his sleep because the first thing he could remember was waking up when his granddaughter stood up to leave the bed.
The court ruled that although it was certain a sexual incident occurred, the man should be acquitted because he was asleep.
“He doesn't remember the incident and has no memory of what happened. He is relieved to be acquitted,” the man's lawyer, Per Wold, told Adresseavisen.
Prosecutors, who were pushing for an eight-month sentence for the man, didn't not immediately say if the verdict would be appealed.