Five people who died in an attack in Norway last week were actually killed by a "sharp object" and not a bow and arrow as was initially reported.
The suspect, Espen Andersen Brathen, shot at people with arrows in Kongsberg, close to the capital, Oslo.
But investigating officers said at some point he either discarded or lost his bow.
It was the worst attack in Norway since far-right extremist Anders Breivik massacred 77 people a decade ago.
Five people were killed with a sharp object both in their own homes and in public spaces, police said on Monday, without giving further details.
In a statement, police said information on the type of weapon used could not be given as not all the witnesses have been questioned yet.
They also said the victims were selected at random, and that a number of people were shot at with arrows at the start of the attack, but none were killed by them.
Mr Brathen has admitted going on a killing spree in Kongsberg on Wednesday.
The suspect, a Danish Muslim convert, is now in custody in a medical facility pending a psychiatric evaluation, but this could take several months.
"As far as motive is concerned, illness remains the main hypothesis. And as far as conversion to Islam is concerned, this hypothesis is weakened," police inspector Per Thomas Omholt told reporters, without elaborating.