"Nobody seen Tupac dead," Knight told KDAY-Radio, Los Angeles, on Friday.
"Maybe the question is ... Pac's not really dead ... Pac's somewhere else."
Knight was with Tupac the night he was gunned down in 1996 in Las Vegas, the New York Daily News said Saturday. Tupac, 25, died nearly a week after the incident. No one has been convicted in his slaying.
Tupac has sold more than 75 million albums worldwide.