Story highlights Domenico Calcagno is one of the cardinals who this week will start to elect a new pope

Calcagno is accused of not kicking a pedophile priest out of the church

Critics of Calcagno now want the cardinal to be disqualified from voting in the conclave

Vatican spokesman: Accusations against Calcagno found to be without foundation by the church and legal system

A plain clothes policeman watches Francesco Zanardi. As he waits for his moment just outside the Vatican in St Peter's Square, Zanardi's intention is clear. So is the policeman's.

The 42-year-old from Savona has traveled 550 kilometers [342 miles] to Rome, determined to make a delivery at the Vatican.

The policeman, however, is just as determined to stop him. Zanardi clutches a red case, emblazoned with a picture of Domenico Calcagno -- one of the cardinals who will elect a new pope in the conclave this week -- across it are the words, "Fuori Dal Conclave" or "Out of the Conclave."

It's stuffed with thousands of signed letters all claiming that Calcagno covered up the serial sex abuse of a priest in northern Italy. They want the cardinal to be disqualified from voting in the conclave. But no one is more insistent than Francesco Zanardi.

When he was an 11-year-old altar boy in 1981 at the Santissime Anunziate church in the town of Spotorno, Zanardi says he was raped by Father Nello Giraudo at least once a week for 5 years. He says many of his school friends also suffered repeated abuse at the hands of Giraudo.

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"I didn't have [consensual] sex until I was 26," Zanardi says in Italian. "I was using drugs, I used to inject heroin. I went into rehab and had counseling, and later realized I was taking drugs because of the abuse."

His quest to reveal the truth behind what happened to him eventually uncovered a cache of damning documents that went all the way to former Pope Benedict XVI.

First Zanardi attempted to prosecute Giraudo for the abuse he suffered but the statute of limitations had expired in his case. So he had to pursue other means of gaining justice. Only last year, Giraudo was convicted for sexually abusing a boy at a Catholic boy scouts retreat in the Piedmont Mountains in 2005.

Giraudo pled guilty and Zanardi was instrumental in the trial. He gave evidence and convinced four boys, who were allegedly sexually abused by Giraudo, to do the same and prove the former priest was a serial abuser. Despite the long pattern of behavior, Giraudo was sentenced as a first-time offender and given a suspended one year prison term. As a witness, Zanardi was allowed to request all the evidence from the court. He was astonished by what he discovered.

On 8th September 2003, Calcagno, who was at the time the Bishop of Savona, wrote to Cardinal Ratzinger who was then the Vatican's enforcer of church doctrine and responsible for investigations into the sexual abuse of minors by clergy.

Calcagno's letter read: "I would request your kind advice on how I should act in view of the fact that the priest intends to continue his pastoral work. As far as possible, I intend to avoid him having any responsibilities which might bring him into contact with children or adolescents."

This letter was accompanied by a church dossier on Giraudo, compiled by then Bishop Calcagno's chief aide, Vicar General, Andrea Giusto. "Nothing has leaked to the papers. No complaints have been filed with the police," read Giusto's report.

"The documents were ugly to read," Zanardi told CNN. The church was concerned with the well-being of a pedophile, but they don't talk about a victim. The victims aren't even taken into consideration the only thing they are trying save is the image of the church."

Despite incontrovertible evidence against Giraudo, Calcagno didn't kick the pedophile priest out of the church. Instead, he was given counseling, sent to work with prison inmates and simply moved from parish to parish. He was even allowed to set-up and run a care home for troubled children in the church rectory. We don't know Cardinal Ratzinger's response to this letter. Two years later -- in 2005 -- Ratzinger became Pope Benedict XVI.

Further documents reveal church officials were aware of Giraudo's crimes from as far back as 1980. On 29th March 2010, Archbishop Ladaria from Thibica wrote to the current Bishop of Savona, Vittoria Lupi. It says Giraudo "was reported in 1980 for abuse of minors" and that Giraudo admitted his own "pedophile tendencies" to the Vicar General of Savona in 2002. Despite all this, it took more than 30 years before the Church forced Giraudo to write a letter of resignation on March 27th, 2010.

Cardinal Calcagno's office declined to give a comment to CNN and in a written statement, the Diocese of Savona, where Giraudo served as a priest, said the Diocese invited him to resign in 2009, but he refused. It went on to say the diocese has been in the forefront of combating abuse by priests.

Vatican spokesman, Rev. Thomas Lombardi is clearly aggravated by our question about the accusations against Calcagno. He folds his arms, leans back and speaks sternly. "The accusations regarding Cardinal Domenico Calcagno when he was Bishop of Savona in Italy were investigated by both the Church and by the legal system, by the judge, and the accusations were without foundation."

Back in St Peter's Square, Zanardi finally makes his move towards the gates of the Vatican but he doesn't get far. The plain-clothes policeman lurking in the background radios his partner and within seconds Zanardi is surrounded by police who lead him away for two hours of questioning.

Zanardi has faced many obstacles in his life but he's not about to give up now just because he's hit another one. He will try to deliver his anti-Calcagno petition at the Vatican Embassy in Rome on Monday. His resolve is undimmed. "What happened to me and many others should never have happened. I will keep fighting until it does not happen again."