"Truly, truly, I say to you, when you were younger, you used to gird yourself and walk wherever you wished; but when you grow old, you will stretch out your hands and someone else will gird you, and bring you where you do not wish to go."
Now this He said, signifying by what kind of death he would glorify God And when He had spoken this, He said to him, "Follow Me!" - John 21:18-19
Jesus signifies in the above verses what type of death Peter would have that would glorify God. Some facts about Peter's death that we can pull from those verses are; Peters death will glorify God, Peter will be clothed by someone else, be taken somewhere he did not want to go, and he would stretch out his hands. How these facts play a part in Peters death we do not know yet.
We also read later in the bible that Peter was aware of his imminent death.
knowing that the laying aside of my earthly dwelling is imminent, as also our Lord Jesus Christ has made clear to me. - 2 Peter 1:14
This above verse is part of the second letter Peter had sent to the church, and at this point at least some would have the knowledge of Jesus's prophecy of Peters death (If they didn't and Peter died, how would it have been passed down? [I am speaking in fleshly terms]). With both these combined I bet Peters death was an item of interest among early Christians. Especially because the early church was under very heavy persecution and Christians were devoting and giving their lives to the gospel.
Jesus prophecy about Peters death is fascinating in that Peters death is not documented in the bible. This compelled me to research any documentation that may contain information helpful in finding out what might have happened to Peter.
I was surprised at how much documentation I found. Keep in mind the documents referenced here are not held as being inspired, some are more reliable than others, and of course all should be held to the light of God's Word.
Though some of the following historical documents can be highly questionable, there is a consistancy that is noteworthy throughout most of them. They all seem to agree that Peter was executed in Rome sometime during the persecutions under Nero (AD 64).
The earliest mention of Peters death is in a letter to the Corinthians from Clement, bishop of Rome (around AD-88-97), He acknowledges both Peter and Paul being martyrs. If this account is accurate, it is so far in accord with what we have read in the bible, that Peters death would glorify Jesus; since the term martyr is defined as someone suffering/dying for their faith. This being the case, it would add a great amount of credibility to Peter's character, and reinforce Peter's testimony of the accounts of Jesus Christ. (and this is even according to worldly judgement). In my research on this subject, this seems to be only one of many accounts that are found from early AD.
In various documents including authors Dionysious, bishop of Corinth (~AD 180), Tertullian, a Christian teacher, (~AD 200), and Caius, 3rd century ecclesiastical writer testify to Paul and Peter both being martyr'd, and a fair amount add that it happened in Rome under the persecutions of Nero. (None of the documentation I found so far contradicted this). Eusebius in his book entitled Ecclesiastical History (Written AD 325) says: "Thus Nero publicly announcing himself as the chief enemy of God, was led on in his fury to slaughter the apostles. Paul is therefore said to have been beheaded at Rome, and Peter to have been crucified under him. And this account is confirmed by the fact, that the names of Peter and Paul still remain in the cemeteries of that city even to this day" (Ecclesiastical History 2:25). So at the time of this writing, Eusebius is stating Paul and Peters graves are still located in Rome. (Almost sounds like he was doing a similar research as we are in this study, but in AD 325)
At least 2 early AD writings mention how Peter died. The first one is Eusebius who I mentioned in the above paragraph, in his writing Ecclesiastical History 3:1, but he says his source is from a church theologian named Origen (Who wrote around AD 230). The second is from the apocrypha which in the early church was dismissed as not being inspired by God; it's not even credited with being a reliable historical document. And since many who have read it would deam it questionable at best, its to be taken very loosely. Supposedly in "The Acts of Peter" , we get the story of Peter being crucified upside-down. It states Peter had requested it this way because he was "not worthy to be crucified like my Lord". Whether true or not, we will not know until we get to ask for ourselves. But if that is the case, it does resemble what Jesus prophecied in John 21:18 when He said to Peter "...you will stretch out your hands..."