(CNN) -- International investigators say there's no evidence that poet Pablo Neruda was poisoned.
Scientists who exhumed Neruda's remains in April revealed details of their investigation last week, confirming that the Nobel prize-winning poet suffered from prostate cancer when he died four decades ago.
But the results haven't stopped skepticism from one member of Neruda's family, who told CNN Chile that he's still pushing for answers about what caused the poet's 1973 death.
"This is a first report that ... opens the door for us to request new tests," nephew Rodolfo Reyes said in an interview with CNN's sister network.
Neruda's death certificate says prostate cancer killed him.
But for years his former chauffeur has offered up another theory, claiming that Neruda was poisoned in the clinic where he was undergoing treatment.
Last week's report from a team of scientists said investigators found "no forensic evidence" to support that Neruda had been killed by anything other than natural causes.
"No relevant chemical agents that could be linked to Mr. Pablo Neruda's death have been found," the report said.
Neruda died on September 23, 1973, just 12 days after a right-wing military coup ousted socialist President Salvador Allende and brought Gen. Augusto Pinochet to power.
The poet, a Communist Party member, had criticized the coup and Pinochet.
Less than two weeks later, he was dead.
He had been planning to go into exile the next day -- and the timing of his death was no coincidence, chauffeur Manuel Araya has said.
"I believe that Pablo Neruda was murdered, because Pablo Neruda was a very relevant figure in history, as much in this country as in the world," Araya told CNN Chile earlier this year. "He was going to go into exile on September 24 and they silenced him before then."
Neruda was a well-known political and public figure, having served as a lawmaker and diplomat in addition to his literary career, which earned him a Nobel Prize in 1971.
Thousands of people disappeared or died during Pinochet's rule, and many have accused his government of using death squads to wipe out political opponents.
Attorney Eduardo Contreras, who represents Chile's Communist Party, told reporters that more tests on Neruda's remains are necessary.
"The Pablo Neruda case is not closed," Contreras said.