Feher died due to 'natural causes'
LISBON, Portugal -- Benfica striker Miklos Feher's death was due to natural causes, Portugal's Attorney General's Office said in a statement.
The Hungarian 24-year-old collapsed during his side's clash with Guimaraes in January and later died in hospital.
An autopsy carried out immediately after Feher's death proved inconclusive, prompting authorities to open a formal inquiry.
But the Attorney General's Office said medical investigators had found no trace of any prohibited substances.
"The blood tests did not reveal any signs of alcohol, drugs, medication or steroids," the statement read.