On Thursday, police in canton Aargau finally arrested the perpetrator of a quadruple murder that had remained unsolved since it occurred in December 2015.
The detainee, a 33-year-old Swiss man residing in Rupperswil in northern Switzerland, has already confessed to the murders, and his fingerprints and DNA were found at the crime scene.
The arrest was the culmination of the efforts of a 40-strong special commission of cantonal police, which led a large investigation that included raids.
“Financial and sexual motives”
On December 21, the man, a student, murdered a 48-year-old woman, her two sons aged 13 and 19, and the older son’s girlfriend, age 21. He then set fire to the house to cover up the crime.
The killer, who acted alone, did not know his victims and has a clean criminal record, said Barbara Loppacher, the prosecutor handling the case. His motives are believed to have been financial and sexual.
The man had carefully planned and executed the murders. On the morning of December 21st, the alleged assassin waited outside the house of his victims until the mother’s partner had left, said Aargau Chief of Police Markus Gisin at a press conference on Friday.
The killer then entered the house, forcing the mother to tie up her son and his friend, before sending her to get money in town. The woman withdrew EUR1,000 ($1,130) and CHF10,000 ($10,250) from two ATMs. On her return, she was also tied up.
The man sexually abused the 13-year-old boy, and then killed his victims by slitting their throats with a knife, before setting fire to the house.
The quadruple murder is one of the most serious crimes committed in Aargau in recent decades. As the perpetrator had no connection with his victims and was not known to police, it took a while to find him, Loppacher said. The authorities did not want to specify exactly how they had discovered his whereabouts.
“We can assume the suspect killed the four people to eliminate witnesses. But he may also have a taste for murder,” a forensic sciences expert told the German-language newspaper Tages-Anzeiger on Saturday.
“The facts described by the police indicate that the man displayed a great degree of self-control, and of domination and sadism.”
The expert indicated that despite the facts of the case, whether or not the killer could also be a paedophile is not yet confirmed.
“This case certainly indicates an instance of sex with a child. But it could also be that the man chose his sexual victim randomly.”
Aargau Chief of Police Markus Gisin said on Friday that police believe the suspect was planning to kill again in the same manner, as several implements including a pistol, a knife, rope, and cable ties were found in his backpack.
The German-language news site Watson.ch interviewed former Basel prosecutor Markus Melzl on Saturday to ask about the possibility of the case having turned up a serial killer.
“In such cases, one must of course do some historical research: is there any documentation on similar cases that have not yet been solved? Prosecutors must…scour all cantons. Maybe there are open cases for which this man could be the perpetrator in question," Melzl said.
"It is interesting that the culprit was preparing a backpack to repeat his act. He prepared a lot of cable ties, which means he did not expect to encounter only one victim. Therefore, he may very well be a serial killer."
swissinfo.ch and agencies