This report in Zenit is very interesting, as the Holy Father himself took the opportunity of today’s feast of Ss Peter and Paul to make the announcement. This is what he said in his homily at the Church of St Paul Outside the Walls where the tomb is located:
“An authentic scientific analysis seems to confirm the unanimous and uncontested tradition that these are the mortal remains of the Apostle Paul.”
“A tiny hole was drilled into the sarcophagus — which over many centuries had never been opened — in order to insert a special probe, which revealed traces of costly purple colored linen fabric, laminated with pure gold and a blue fabric with linen filaments,” Benedict XVI explained.
“Grains of red incense and protein and chalk substances were also discovered,” he continued. “There were also tiny bone fragments, which were sent for carbon-14 testing by experts who were unaware of their origin. These were discovered to belong to a person who had lived between the first and second centuries.”
The Zenit report has other interesting facts about the tomb which you might like to read.