A riot police officer who died during crowd trouble before a Europa League football match in Spain collapsed on his own and was not involved in a direct confrontation with fans, authorities said.
Basque Country officials said doctors dismissed the possibility the cardiac arrest suffered by the officer was caused by any type of trauma sustained in the fighting that took place ahead of the tie between Athletic Bilbao and Russian club Spartak Moscow on Thursday.
There had been conflicting reports about what caused the officer's death, with some saying he might have been involved in a struggle with fans or was hit by one of the many objects being thrown around during the altercation.
Police said today five people remained detained - three Russian nationals and two Spaniards.
Bilbao lost the match 2-1 on the night, but progressed at the Russians' expense 4-3 on aggregate.