The theft of a handwritten letter by the Renaissance master , Michelangelo could only have been an inside job , the former head of the Vatican museums has said . The return of two letters stolen from an archive in 1997 , has been offered by a former Vatican employee for between euro 100,000 ( £72,000 ) and 200,000 ( £144,000 ) . The Vatican authorities discovered that it was missing from the offices of the Fabbrica of St Peter ’ s Basilica 18 years ago but did not publicise the theft . The Former director of the Vatican Museums has said the theft of letters written by Michelangelo from its archives must have been carried out by 'an inside man ' . Above , a file image of one of its archives . Former director of the Vatican Museums , Franco Buranelli , said : ‘ These areas [ of the archive ] are not easy to access . 'It must have been an inside man working in the archives who knew how to gain possession of the document and be able to get it out without creating havoc. ’ He said the letter was of ‘ immense ’ value although it would be impossible for thieves to sell . ‘ Every letter by Michelangelo is of immense value . The loss of any nugget by the great Renaissance masters is serious . ‘ There is no realistic prospect of a sale ’ , he told Rome-based newspaper Il Messaggero . But in any case the value of the letter ‘ is difficult to estimate because it depends on ‘ the content , intended recipient , period and the presence or not of signatures , sketches , designs or sonnets. ’ He said that the letter would probably not have been a family letter but likely referring to art commissioned by the pope . ‘ It could be on architectural matters or a service note for the acquisition of materials that he needed to complete a work. ’ Mr Buranelli said while the letters could not be sold they were of 'immense value ' . A former employee has come forward almost 15 years after they were stolen , claiming he knows where they are . A nun working in the Archivio della Fabbrica , the body set up by Pope Julius II in 1506 to maintain the basilica of St Peter ’ s informed the then head-Cardinal Noe of the disappearance in 1997 . Then a few months ago an ex-Vatican employee contacted its head , Cardinal Angelo Comastri , saying he knew what had become of the letter and wanted a reward . ‘ Cardinal Comastri recently received a proposal for the return of the letter in exchange for payment , ” Father Federico Lombardi , the Vatican spokesman , said . ‘ Naturally he refused , as these are documents that have been stolen . ’
Letters were kept in an area of the archives which few had access to . Franco Buranelli said they must have been lifted by 'an inside man ' The documents , said to be of 'immense value ' were stolen in 1997 . Former Vatican employee said this year he knew where they were . He has demanded one euros to return them .