How does an inverted crucifix relate to Saint Peter?

A Cross of Peter is an inverted Latin cross The Cross of Saint Peter or Petrine Cross is an inverted Latin cross traditionally used as a Christian symbol, but in recent times also used as an anti-Christian or Satanic symbol. read more

As a result of the manner in which he was crucified, the Church has used the upside down cross (without a corpus, so not a crucifix) to designate Peter, not Christ. The Pope, being the successor of Peter, employs the symbol of the upside down cross as a symbolic reminder of St. Peter's humility and heroic martyrdom. read more