A post mortem on David Hockney's assistant and friend Dominic Elliott has shown "no obvious natural causes for his death," Humberside Police has said.
Further tests will now be carried out, but their results will take some weeks.
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A judge ruled the boy may be allowed home from Alder Hey Children’s Hospital, but will not be allowed to go to Rome for further treatment.
Alek Minassian, 25, has been charged with first degree murder.
The president, meanwhile, thanked the French leader for his “steadfast partnership” in the recent missile strike in Syria.