An Argentinian judge has started an investigation into the death of Spanish poet and playwright Federico García Lorca, who is believed to have been executed in 1936 during the Spanish civil war by forces loyal to General Franco.

A site near the Spanish city of Granada where he was believed to have been buried was excavated in 2009 without finding human remains.

A Spanish human rights group, the Association for the Recuperation of Historic Memory, asked Argentinian federal judge Maria Servini to take up the case. “The case has been incorporated into an ongoing investigation by Judge Maria Servini into crimes against humanity,” the group said. A Spanish human rights judge, Baltasar Garzón, opened an inquiry into Franco-era crimes in 2008 but later dropped the case.

García Lorca was born in 1898 in a small town near Granada. His first poetry collection was Libro de poemas, a compilation based on Spanish folklore. In the 1920s he became part of a group of artists known as Generación del 27, which included Salvador Dalí and Luis Buñuel. In 1928, his poetry collection Romancero Gitano brought far-reaching fame, and was reprinted seven times during his lifetime.

Last year newly-released documents revealed that he was arrested and killed on the orders of rightwing military authorities in Granada. The documents, written in 1965 at the Granada police headquarters and obtained by the Guardian, relate to an inquiry into García Lorca’s death by a French author in the 1960s.

The documents suggest García Lorca was persecuted for his beliefs, describing him as a “socialist and a freemason,” about whom rumours swirled of “homosexual and abnormal practices”. After police twice searched his home in Granada, he fled to a friend’s house. In August 1936, a month after the civil war broke out, officers surrounded the house where he was hiding. He was arrested and taken by car to an area close to the place known as Fuente Grande, along with another detainee, said the documents. He was then “executed immediately after having confessed, and was buried in that location, in a very shallow grave, in a ravine”. No details were given as to the content of his confession.

Since 2009, several attempts have been made to locate the grave where García Lorca is thought to lie. So far archaeologists have had little success. The excavations were not only about finding Lorca, stressed Juan Francisco Arenas of the regional government of Andalucía in 2014. “There are believed to be some 3,500 missing people buried in the area,” he said. “We’re not just looking for one person, but for all of them.”

Lorca was one of the most famous victims of Franco’s nationalist forces. “But finding Federico Lorca is like finding a needle in a haystack,” he said.