“We believe that the period of uncertainty for the people of Bodenfelde is over,” said district police chief, Hans Walter Rusteberg, at a press conference in the Lower Saxony city of Northeim Wednesday morning. “The people no longer need to fear leaving their houses after dark.”

The head of the murder inquiry, Hartmut Reinicke, added: “We are absolutely certain we have the right person.”

Suspect Jan O., 26, is according to police “strongly suspected” of having murdered two teens, Tobias, 13, and Nina, 14, whose bodies were found in a secluded wooded area on the outskirts of Bodenfelde on Sunday.

Police told news agency DAPD that Jan O. had the ”potential to be a serial killer” and already may have had a third victim in mind.

Reinicke said 26-year-old Jan O. had approached another girl on Saturday afternoon in a car park. He had wanted to swap mobile phone numbers with her. Police said he may have been trying to lure the girl. She accepted his number and then informed police.

An internet search then yielded further clues about the suspect.

“This was crucial for the investigation,” said Reinecke. Investigators then found blood stained and soiled clothing during a search of Jan O.’s home.

The two teenagers had died from a combination of stabbing and strangulation, criminal director Andreas Borchert said, according to news magazine Der Spiegel.

State prosecutor Hans Hugo Heimgärtner said Jan O.’s lawyer had indicated he wanted to make a confession.

Police late on Tuesday secured a warrant to hold the unemployed 26-year-old, who has a history of drug and alcohol abuse.

Investigators arrested him on Monday evening on a train at a Bodenfelde station just as it was due to depart.

More than 600 people gathered on Tuesday night for a church service for Nina and Tobias.

Jan O. went to a school for people with learning disabilities and lived until recently in a facility for drug addicts, Bild reported. Since he was discharged, he has been under supervision, news agency AFP reported. He has previous convictions for petty theft.

Bild reported that Jan O. used social networking websites to contact children and teens. On a youth networking site, he had 20 friends, among them 18 underage girls.

Under the photo of a 14-year-old he had written: “You’re really cute. Horny little toes. Would like to nibble on them.”

He repeatedly asked young girls to contact him.

“Any girl between 10 and 16 interested in chatting and maybe more, please register,” wrote in one post. In another, he wrote: “Seeking girls between 10 and 14.”

A 14-year-old female friend of the man told the paper: “He was really nice … but when he was drunk, I was afraid of him. Then he was brutal and, during a fight, said, ‘I’ll hit you in the face.’”

He had often been drunk and used drugs, people who knew him said. He had also carried a knife.

The dead girl, Nina, had been part of the group of youngsters whom Jan O. had hung around. However, there is no apparent connection with the boy Tobias.

DPA/The Local/dw