Police said on Friday that the suspect in the case in Herne, North Rhine-Westphalia had confessed to both the murder of a nine-year-old boy and an acquaintance this week.

Marcel H., 19, was arrested on Thursday after a nationwide, days-long, intensive manhunt following the gruesome discovery of a young boy stabbed to death in a basement on Monday. Images surfaced online, including an apparent selfie of the bloody suspect with the dead boy's body, and led to someone alerting police about the crime.

The suspect turned himself in on Thursday by telling workers at a local eatery to call police. He then gave officers information to lead them to an apartment fire, where a second victim was discovered.

On Friday after a long interrogation session with the suspect, officials detailed what Marcel H. had confessed led to his violence: his frustration about potentially losing internet connection and being rejected by the German army.

“I have little doubt about what he says, but we cannot trust him in all areas,” said the leader of the Bochum homicide unit,  Klaus-Peter Lipphaus.

He told police that initially he had tried to kill himself. The suspect said he had been feeling frustrated because his application to the German army was rejected. He was also upset because his family was moving to another town, and he feared losing his internet connection.

The possibility of “not being able to play video games online” made him contemplate suicide.

But when his suicide attempt failed, Marcel H. decided to kill someone else, and that turned out to be his nine-year-old neighbour, Jaden, who he stabbed more than 50 times.

After killing Jaden, Marcel H. said at first he hid in a forest and then went to stay at the home of the second victim, who he knew through their technical college. The two had been in touch via online chats. Marcel H. and the victim played video games and ate meals together.

But then, Marcel H. decided to kill his host because the 22-year-old friend wanted to go to police about the first murder, stabbing the young man more than 60 times.

After killing the acquaintance, Marcel H. initially did not leave the apartment, staying with the dead body for two days before turning himself in on Thursday. He decided to turn himself in because he said he no other alternative, other than to kill himself.

How the suspect set fire to the apartment in which the second victim was found is not yet clear.