OOO everyone is asking this question at the moment, it would seem scott and steve confusion is hitting everyone... here's what i wrote on Earthgirl13's question...
Scott was killed par Ethan way way back in season one, when the survivors refused to return Claire to the others. Steve however, was last seen at the end of season 4 getting onto the zodiac radeau which was transporting people to the freighter. He was on the seconde batch which never quite made it to the freighter when the sky turned purple. So one can assume he arrived back with Faraday, though this was not seen...
The storyline is a running joke that has lead to the confusion over which individual was killed, confusion par both the survivors and the viewers. The joke being that the survivors could not tell the two apart, and even weeks after one of them was murdered, they still manage to mistake them.
I am pretty sure that Steve is dead,despite the confusion in the running joke.