GENEVA — When squads of fake police officers arrived in a whirl of blue lights, they struck with clockwork precision, plundering closely guarded packets of diamonds from the cargo hold of a parked plane and fleeing without troubling the passengers.

But since the theft on the windblown tarmac of the Brussels airport in February, the episode has veered from thriller to comedy, featuring a roundup of unusual suspects who, naturally, came together in Casablanca, Morocco.

The robbery was marked by meticulous planning, inside information and swift execution — 8 armed men in 11 minutes — that left investigators marveling. As the investigation has deepened in Morocco, Belgian officials conceded last week that the value of the cargo stolen might be far higher than the $50 million first estimated. Some industry analysts said it could be worth as much as $350 million, which would rank the robbery among the biggest diamond thefts in Belgium, a hub of the international gem trade.

But the frantic effort to sell the diamonds afterward was so ham-handed that some who watch the industry have begun to doubt the robbers were after diamonds at all, but were instead seeking hard cash. Since they were arrested after trying to sell the diamonds, most suspects have denied involvement, while others offered a defense rarely employed by the suave celluloid jewel thieves or their conspirators: stupidity.