The police began their investigation against Eskilstunabon, who was previously convicted of child pornography, after observing him on the darknet in December 2017. In January 2019, a raid was made on the man's home, where large amounts of encrypted material suspected of being child pornography were discovered.

As the material could not be made available to the police, the man was released after questioning and then stopped at customs at Arlanda in December of the same year.

With him from Thailand, the man had a hard drive that was suspected of containing child pornography.

Even then, the man was released after questioning.

- Getting into encrypted files is often time-consuming, and after the second attack, the infiltration phase of the investigation began, prosecutor Emelie Källfelt says.

Pretended to be a pedophile

By pretending to have a sexual interest in children and chatting with Eskilstuna residents, the police infiltrator succeeded in gaining the trust of the man now accused.

It appears from the investigation, which has been carried out in part by NOA, the police's national operational department.

Excerpt from a chat conversation between the police infiltrator and the suspect Eskilstuna resident.

The infiltrator is invited to be involved in an abuse of a child.

The resident of Eskilstuna must then have put the infiltrator in contact with the then unpunished Stockholm resident, in order to allow the infiltrator to commit abuse against his children.

During the meeting, the man was arrested by the task force, and in close proximity, the man from Eskilstuna was also arrested.

The man from Stockholm has consistently denied any wrongdoing, while Eskilstunabon has denied or chosen not to comment on the charges.

Controversial method

Criminal provocation is illegal in Sweden, but provocation of evidence is allowed.

Where the line between the two forms of provocation goes is determined by case law rather than law.

- I do not want to comment on the upcoming trial in advance, but in general it can be stated that there is in principle no legal regulation that governs how one may use this.

I think the state will have to regulate that eventually.

At the moment, it is a seesaw that gives rise to a lot of discussions and conflicts, says Eskilstunabon's lawyer Lars-Åke Chorell.

The trial against the two men is expected to last for three weeks.

Hear Christer Nilsson, operations manager at NOA, talk about the infiltration operation in the clip above