His plan was to get the husband arrested so that he could have a go at a relationship with the woman, and to do this he broke into the couple's home while they were sleeping, used their family computer to download child pornography and then removed the hard drive and mailed it anonymously to the police, along with a note that identified the owner.
The whole family received a shock when the police came and arrested the husband on suspicion of possession of indecent images of children. He was banned from seeing his own children and from returning to his home while he was under investigation.
Luckily for him, a search of Karttunen's home revealed evidence about the real perpetrator of the crime. Before sending the hard disk to the police, he downloaded its contents onto his computer, which he kept in the garden shed. A lot of personal information like pictures and credit and debt card information belonging to the family was discovered on it after the computer was analyzed.
Times Online reports that they also found evidence of him having repeatedly broken into the family's home and taking pictures of a child's bedroom and a calendar on which the working schedule of the husband was marked.
“The lengths this man went to in order to pursue a fantasy were incredible," remarked the case prosecutor. Aside from the prison sentence, he was also slapped with a restraining order and is now signed into the sex offenders register.