The state charges against John Antwan Caver, 29, were dropped Tuesday, but he could face federal charges if he is indicted by a grand jury, said Clark County prosecutor Susan Krisko.
Caver's lawyer did not immediately return telephone messages.
U.S. attorney's office spokeswoman Natalie Collins said Tuesday that no charges had been filed against Caver or alleged accomplice Fred Ball, 45. She declined to say whether the grand jury was hearing the case.
State charges against Ball were dropped in September.
Authorities had alleged that Ball served as a lookout while Caver set the May 29 fire that destroyed the rundown casino about a mile northwest of the downtown gambling district. It was the city's first to welcome black customers excluded from the Las Vegas Strip.
Three people were hurt in the blaze, which raged for hours and left little standing but the casino's marquee.
