Return of the Living Dead: Necropolis, the fourth film in the series, was filmed in Romania and Ukraine. The film stars Peter Coyote and Aimee Lynn Chadwick. The plot revolves around a group of teenagers attempting to rescue their friend from an evil corporation. In doing so, they wind up releasing a horde of blood thirsty zombies. An edited version of the film aired on the SciFi Channel on October 5, 2005. The R-rated version of the film was released on DVD on April 18, 2006. The film was originally advertised as Return of the Living Dead 4: Necropolis but once it was finally released, the number 4 was removed from the title. Both Necropolis and Rave are critizised for straying away from the series' rules.
Most notable of these changes is that Trioxin zombies are no longer the indestructible juggernauts of the first movie, but instead much weaker than even "Romero zombies." Several times throughout the movie they are seen to be dispatched with no more than a few body shots, sometimes as few as two hits will end their undead life. Prior to this film nothing short of incineration or electrocution with extreme high voltage would terminate a trioxin zombie.
However, this may be a different form of Trioxin; here, it is referred to as "Trioxin 5," which may explain why the zombies are weaker