So was that thief hanging beside Christ saved?
Which one? There were two and granted the bad one put the Lord to the test, not the best thing to do break a commandment as your last act on earth. But even for the bad thief isn't being crucified repentance enough for his sins? Does he really burn in hell for eternity because he did not fully understand the Gospel and Christ's standing as Messiah?
And yes the good thief is saved Christ says "this very day you shall walk with me in paradise."
Why do you doubt it?