Officials said soon after the collapse that numerous construction regulations had been violated.
Abdul Halim, an official with Savar's engineering department, said the owner of Rana Plaza was originally allowed to construct a five-story building but added another three stories illegally.
Home Minister Muhiuddin Khan Alamgir has said the building violated construction codes and that "the culprits would be punished." Local police chief Mohammed Asaduzzaman said police and the government's Capital Development Authority have filed separate cases of negligence against the building's owner.
Habibur Rahman, police superintendent of the Dhaka district, identified the owner of the collapsed building as Mohammed Sohel Rana, a local leader of ruling Awami League's youth front. Rahman said police were also looking for the owners of the garment factories.
The disaster is the worst ever for Bangladesh's booming and powerful garment industry, surpassing a fire five months ago that killed 112 people and brought widespread pledges to improve the country's worker-safety standards.
Instead, very little has changed in Bangladesh, where wages, among the lowest in the world, have made it a magnet for numerous global brands.
Bangladesh's garment industry was the third-largest in the world in 2011, after China and Italy. It has grown rapidly in the past decade, a boom fueled by Bangladesh's exceptionally low labor costs. The country's minimum wage is now the equivalent of about $38 a month.
Among the garment makers in the building were Phantom Apparels, Phantom Tac, Ether Tex, New Wave Style and New Wave Bottoms. Altogether, they produced several million shirts, pants and other garments a year.
The New Wave companies, according to their website, make clothing for several major North American and European retailers.
Britain's Primark acknowledged it was using a factory in Rana Plaza, but many other retailers distanced themselves from the disaster, saying they were not involved with the factories at the time of the collapse or had not recently ordered garments from them.