SAVAR, Bangladesh — Barely 20 miles from the national capital, this gritty suburb is now a dusty, chaotic industrial center littered with factories that produce clothes for leading Western brands. Building codes are often unenforced, regulatory oversight is flimsy and the men wielding power often travel with armed guards.

And perhaps no one wielded power more brazenly than Sohel Rana. He traveled by motorcycle, as untouchable as a mafia don, trailed by his own biker gang. Local officials and the Bangladeshi news media say he was involved in illegal drugs and guns, but he also had a building, Rana Plaza, that housed five factories.

Upstairs, workers earned as little as $40 a month making clothes for retailers like J. C. Penney. Downstairs, Mr. Rana hosted local politicians, playing pool, drinking and, the officials say, indulging in drugs.

Now Mr. Rana, 35, is under arrest, the most reviled man in Bangladesh after the horrific collapse of Rana Plaza last week left nearly 400 people dead, with many others still missing. On Tuesday, a top Bangladeshi court seized his assets, as the public bayed for his execution, especially as it appears that the tragedy could have been averted if the frantic warnings of an engineer who examined the building the day before had been heeded.