June 6, 2013 -- Nearly 40 years after the fact, Pablo Neruda's death still bewilders Chilean authorities.

Neruda, a Nobel laureate described by famed Mexican author Carlos Fuentes, as "the first great poet of the Spanish language since the 17th century," died in September 1973 of apparent natural causes. But in 2011 the Chilean Communist Party filed a civil case arguing that Chile's most important literary figure was in fact murdered by a mysterious agent of the country's right-wing dictator, Augusto Pinochet.

Deepening the cloak-and-dagger mystery, that murderous agent has been alternately identified as a supposed CIA double-agent, a child-abusing Nazi, and a shady doctor who tortured prisoners for Pinochet's government.

It is worthy "of a police novel," Neruda's nephew told Ritmos XXI, a cultural newspaper.

According to his death certificate, Neruda -- an ardent Marxist who upended the global literary establishment and his country's popular opinion with his politics -- died of prostate cancer at the Santa María Clinic in Santiago. He had undergone surgery for the condition two months earlier. But, according to the official story, his condition took a turn for the worse after September 11, 1973, when president Salvador Allende -- a close friend of Neruda's -- was killed during a bloody CIA-backed coup. But lawyers for the Communist Party and Neruda's family give a different account, based on testimony by Neruda's driver, Manuel Araya, who claimed that a man had given Neruda a strange injection shortly before his death.

The Santiago appeals court that took the case began calling back some of the original witnesses, many of which had been interviewed by journalists and wary members of the Communist party back in the day. One of the first to testify was Sergio Draper, Neruda's doctor at Santa María.

In the 1970s, Draper had said that he was with the poet at the time of his death. But now, according to Communist Party lawyer Eduardo Contreras, one of the few people who has access to the closed-door testimonies, Draper says he handed Neruda's care over to a mysterious figure known as "Dr. Price."

Price has become the central figure in alternative accounts of the poet's death, and a man wanted by Chilean authorities both in and outside of the country. A tall, blond, blue-eyed man who, according to hospital personnel, was estimated to be roughly 27 at the time, Price is the man who allegedly injected Neruda with an unknown substance that prompted his death.

"He is like a ghost," Rodolfo Reyes, a lawyer for Neruda's family, recently told news site, La Tercera. Price's name does not appear in the hospital's registries, and authorities have not been able to locate him despite the court's demands to question him.

Chilean police used Draper's description to create a sketch of the alleged murderer. The black-and-white portrait depicts a clean-shaven man with thin lips and short hair, a vague semblance that nonetheless has already been linked to three sensational suspects. According to Contreras and Reyes, the suspects who fit Dr. Price's description include Michael Townley, a U.S. citizen who, according to declassified documents, worked as an assassin for Pinochet's secret service; Harmutt Hopp, a German convicted in a pedophilia scandal at a Chilean commune with Nazi ties; and Manfred Jurgensen, a doctor who collaborated with Chilean intelligence.

Townley, who is currently a part of the U.S. government's witness protection program, worked as a weapons manufacturer for Pinochet's nefarious Directorate of National Intelligence (DINA). According to declassified FBI documents, Townley had ties to Italian terrorists and is suspected of playing a role in the disappearances and murders of several of the Chilean regime's opponents.

Townley was also described as a double agent working for the CIA by Manuel Contreras, DINA's director (who is unrelated to Eduardo Contreras). But that characterization served a political purpose, according to John Dinges, a Columbia journalism professor who covered the region during those years and wrote several books about Chile.

"This is a story that Manuel Contreras has been putting out consistently since the death of Letelier: that Townley was not working for DINA but for the CIA," Dinges told the AP. "And the left falls into the trap again and again, because they want to throw mud at the CIA."

Moreover, according to Dinges and other experts, several documents show that Townley was in the U.S. when Neruda died, so it is highly unlikely that he is the mysterious Dr. Price.

Hopp's and Jurgensen's cases are tougher to dismiss. A third source, an anonymous doctor who reportedly worked in the clinic at the time, corroborates what Reyes and Contreras have said about their likeness to the portrait of Dr. Price and both men have extensive criminal records.

Hopp, 68, is a German doctor who was the second in command at Colonia Dignidad, now known as Villa Baviera, a cult-like commune located in central Chile. Founded in 1961 by Paul Schäfer, a Wehrmacht doctor with ties to the Nazi party who fled to South America in 1959 after being accused of child abuse, Colonia Dignidad housed hundreds of German immigrants. It also served as a jail and torture center for political prisoners throughout Pinochet's dictatorship. Hopp was convicted of child abuse and sentenced to prison in 2011, but he fled to Germany, where the government has refused to allow his extradition to Chile.

Jurgensen was a well-known doctor who was stripped of his degree after it was revealed that he was an agent for the Central Nacional de Informaciones, an intelligence organ created by Pinochet. Jurgensen allegedly helped to torture prisoners in secret detention centers and he was involved in the death of Federico Alvarez Santibáñez, a 32-year-old chemistry professor who was disappeared in 1979. So far, the case against both men is wholly circumstantial: There is no evidence to suggest that they were present at the Neruda's hospital or that they were charged with a mission to kill the poet.

The investigation is still ongoing, and the Chilean people are still waiting for an answer. The dictatorship created a divide among the population that hasn't disappeared; for the left, Neruda has become an important symbol of resistance and greatness, like Federico García Lorca in Spain.

Neruda, whom famed author Jorge Luis Borges called a "very fine poet" and a "very mean man," was a staunch supporter of communism in Latin America. He opposed U.S. involvement in the continent's politics and used his position as one of the world's leading literary figures to advance his beliefs. Revealing a conspiracy behind his death has become a calling for groups like the Chilean Communist Party.

Neruda's body was exhumed last April from its resting place in Isla Negra. The remains were sent to the U.S., and the first test results are already in. Thus far, they have confirmed only one thing: that Neruda was indeed suffering from advanced prostate cancer.