I would imagine that St. Peter let it be known that Linus would make a good successor, but that the college of bishops elected a new pope at the death of St. Peter in 69.A.D.  It is interesting that St. Peter did not choose St. John the Divine as his successor, as he was Our Lady's priest and obviously still living.

But it seems that many Catholics have this mistaken idea that the college of Cardinals is incapable of electing a malicious bishop, and I do not see it.  Going back to the Siri thesis, if Siri was elected, but told the Cardinal dean, "non accepto," because he felt his life was threatened, and then the cardinals said to themselves, "Well, we know that Siri is a good candidate, and he is conservative, but the liberals will probably kill him, so we are going to elect Roncalli, even though he is a liberal."  Why is this not a valid election?  At the end of the day, if the cardinals are liberal, then we are stuck with a liberal pope.  The only escape from this dilemma is to pray harder for an orthodox pope. 

These modern popes present a special difficulty because of the new rites of priesthood and episcopal consecration.

When there is a plot to intimidate a new, validly elected Pope, who has accepted the Seat and taken a papal name, that Conclave is invalidated.  

And no alternate papal candidate is valid until the injustices from the breached Conclave are rectified by the College of electing Cardinals. 

In 1958, Roncali held the Conclave Cardinals to an oath of secrecy.  Highly irregular. Cardinal Siri spoke of this oath not long before his death.

It appears Cardinal Siri won the 1963 Conclave, again with “White smoke”, but was put aside.  

By 1978, he was still the favorite but by this time ecclesiastical masonry had perfected the rigged papal election.