The man who opened fire in a Zurich mosque had earlier killed an acquaintance with a knife before beginning the shooting spree, investigators say.
"There are no indications that terrorism was involved," prosecutor Francoise Stadelmann said. The 24-year-old Swiss suspect was apparently interested in the occult.
However, investigators said they did not know the motives for the stabbing at the weekend or for the shooting that left three injured on Monday.
A passer-by had discovered a young dead man with stab wounds at a Zurich playground on Sunday.
The suspect had left DNA traces, and investigators quickly identified him as an acquaintance of the victim, said Christiane Lentjes Meili, Zurich's criminal police chief.
The two men who were about the same age had an argument prior to the killing, she said.
When police searched the suspect's empty home on Monday, they found knives and symbols that pointed to the occultist interests of the man, who was partly of Ghanaian descent.
"There were indications that the perpetrator was interested in occult topics," Lentjes Meili said.
On Monday evening, the man entered a small mosque in central Zurich and shot at a handful of men who were drinking tea after praying.
Three men were injured, two of them seriously.
The suspect escaped, and police launched a manhunt, without knowing at first that the shooter was the same man who was wanted for the lethal stabbing.
A few hours after the attack, they found a dead male near a river, only 400 metres away from the mosque.
He appeared to have died by suicide.
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