Rome, Italy (CNN) -- A Nigerian man who sang in a Vatican choir arranged gay liaisons for an Italian government official who served in the unpaid role of papal usher, according to transcripts of wiretaps collected by Italian authorities. 

The wiretaps were gathered as part of an investigation into how public-works contracts were awarded. 

The purported conversations were between Angelo Balducci, who oversaw the Italian government's awarding of construction contracts -- including work on the airport at Perugia -- and Thomas Chinedu Ehiem, a 39-year-old Nigerian singer. They were recorded between April 14, 2008, and January 20, 2010. 

In addition to working for the government, Balducci served as a "gentleman of his holiness," also known as a papal usher or "Vatican gentleman." The main responsibility of the ceremonial position is to welcome heads of state to the Vatican and escort them to see the Pope. 

Balducci is one of three public officials who, along with a businessman, have been jailed on charges related to corruption in the public works department. The public officials are alleged to have awarded contracts to businessmen who offered them favors, money, sex, and/or house remodeling in exchange. The suspects, who deny the charges, are in "cautionary custody" though they have not been charged or indicted. 

The Italian news media have nicknamed the scandal "grande opere," which translates as "big works." The transcripts of the wiretaps were made public on Wednesday and widely disseminated in the media. 

Balducci's lawyer, Franco Coppi, lambasted investigators' handling of his client. 
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arranged gay liaisons for an Italian government official who served in the unpaid role of papal usher