The gun used by a would-be assassin to shoot Pope John Paul II will be on display at a Polish  museum dedicated to the pontiff.

John Paul II, who died in 2005, is to be proclaimed as a saint April 27 at the Vatican and the museum is preparing a new exhibition for the occasion.

Monsignor Jacek Pietruszka, who is in charge of the museum, said Wednesday that many people wonder why trained assassin Mehmet Ali Agca, firing a Browning HP 9mm handgun from close range, injured but did not kill the pope in St. Peter's Square on May 13, 1981.

Bulgaria was also allegedly involved in the attempt on the Pope's life. After his arrest Agca claimed he got help from three Bulgarians – Sergei Antonov, Zhelyu Vasilev and Todor Aivazov.  

Antonov, who at the time was working in the Bulgarian flag carrier airline BGA Balkan in Rome,  was arrested in 1982 and tried for complicity in the assassination attempt. 

Vasilev and Aivazov, who were working in the Bulgarian embassy at the time of the shooting, had already left for Sofia. Antonov spent four years in Italian prison and was eventually acquitted due to lack of evidence and released. Antonov died in Sofia in 2007. 

John Paul pardoned Agca, who was released from prison in 2010.

The gun — on three-year lease from Rome's penal authorities — and a replica of the bullet will be among "witnesses" to the happy and sad moments in the late pope's life that will be documented at the multi-media museum in John Paul's childhood home in Wadowice, in southern Poland.

The current, small exhibition at the house where the pope was born in 1920 as Karol Wojtyla, will close this week to give room for the expanded museum that will reopen on April 9.