Polish researchers on Tuesday exhumed the body of Stanislaw Pyjas, an anti-Communist activist who died in mysterious circumstances in 1977, DPA reported.
The body was exhumed in Gilowice, southern Poland, and was later to be taken to Krakow for testing.
Pyjas was found dead on May 7, 1977 outside a Krakow apartment. Prosecutors at the time said Pyjas had "fallen down the stairs." It was suspected Pyjas was killed by the secret services of Poland's then Communist government, but investigations in 1991 and 1999 were dropped due to lack of evidence.
The current investigation was launched by prosecutors after new evidence emerged. It is the fifth probe into the death. Researchers did not say how long the investigation would take.
Pyjas was a student at Krakow's Jagiellonian University, and a member of the Workers' Defence Committee, which helped organize protests against Poland's communist regime.
Prosecutors were given the nod to exhume the body on March 18 from Janusz Kurtyka, head of the Institute of National Remembrance, which investigates Nazi and Soviet crimes.
Kurtyka said the investigation would settle the "mechanisms and reasons" of the student's death.
Kurtyka was one of the 96 victims who died in a plane crash on April 10 in Smolensk, Russia that also killed Polish President Lech Kaczynski and dozens of politicians.