Most of the clues come from the United States.
The perpetrators are also located in Germany and are increasingly being targeted by the police.
In Berlin, the State Criminal Police Office (LKA) carried out a major raid against consumers and distributors of child pornography.
Investigators have searched more than 40 apartments and other rooms since early Wednesday morning, the police said.
It is about the suspicion of the use and distribution of child pornography images, i.e. images of serious sexual abuse of children.
The 42 suspects are all men, said Norma Schürmann, responsible department head in the LKA. They are between 17 and 84 years old. Two thirds of the men are said to be known to the police, half have already been suspected of having committed sexual offenses. 250 police officers were on duty. The searches are not about related cases, but about single investigations, said Schürmann. The aim is to seize computers, cell phones and other data carriers. There were no arrests. A first balance sheet should be presented at 1 p.m.
There were 300 similar searches in Berlin last year, according to the LKA.
"The probability of being caught is getting higher and higher for the perpetrators when it comes to child pornography," said Schürmann.
In the USA, network operators would use algorithms to crawl data traffic and report suspected cases and their IP addresses to the National Center for Missing and Exploited Children (NCMEC).
The IP addresses are then forwarded to other countries.
The BKA receives tens of thousands of notifications every year
“The majority of suspected cases in Germany are reported by NCMEC. There are now an incredible number of procedures, ”said Schürmann. The BKA receives tens of thousands of reports annually and forwards them to the state criminal investigation offices. Due to changes in the law, the German operators will also be obliged to carry out such automated scanning of data traffic in the future.
At the Berlin LKA, the responsible departments have been expanded and staffed due to the increasing number of cases, said Schürmann. Further individual searches and raids are to be expected again and again. The investigating Kripo officers all worked voluntarily in the area of sexual offenses. The evaluation of so many seized computers and cell phones could then take up to a year, countless pictures and films would have to be viewed, evaluated and described for public prosecutors and courts.
The LKA department head Judith Dobbrow said the perpetrators would exchange pictures and films worldwide.
Often there is private contact with the victims.
Relatives would take photos of children and post them on the Internet.
Many perpetrators would feel safe, especially in the so-called Darknet, in which one can move isolated and anonymously.
Be careful with your own pictures
In addition, there is the problem that adolescents and children would unwittingly exchange their own and other people's pictures in chat groups, said Dobbrow.
"You have no awareness that abuse can be behind it." You can only ask all parents and children to be very careful with their own pictures.
During the searches in the area, the police proceeded inconspicuously and without uniformed forces, said Schürmann.
"It's not about pillorying the suspects, because exculpatory evidence can also be found."
As recently as the beginning of May, the Bavarian police searched 49 objects in a child pornography raid, and 51 suspects were identified.
The perpetrators come from "all age groups, all professional groups, all social classes and all regions," it said.
Shortly before, the BKA had announced that one of the world's largest child pornography platforms on the Internet had been broken up. Several men were arrested as suspected operators in Germany. The darknet platform is said to have had more than 400,000 members in many countries. The shared image and video recordings also included recordings of the most serious sexual abuse of young children.