A labor organizer who helped ABC News expose dangerous working conditions at garment factories in Bangladesh was tortured and killed last week, according to authorities. "All indications are that Aminul Islam was murdered because of his labor rights work," said Scott Nova, executive director of the Worker Rights Consortium, an American group working to improve conditions at factories abroad that make clothes for U.S. companies. "This depraved act signals the deterioration of an already grim labor rights situation in Bangladesh, which is now the fourth largest exporter of apparel to the U.S." Islam had been serving as a senior organizer for the Bangladeshi Center for Worker Solidarity (BCWS), and had most recently been involved in efforts to organize workers at garment factories owned by a company called the Shanta Group. According to shipping records, the company makes clothing for numerous well-known American companies, including Tommy Hilfiger, Nike, and Ralph Lauren. Islam had also helped arrange interviews for ABC News with survivors of one of the deadliest recent factory fires in Bangladesh -- interviews featured in a recent report that aired on "Nightline" that focused on designer Tommy Hilfiger and the parent company that manufactures his clothing line, PVH Corp. Bangladesh is currently the cheapest place in the world for garment manufacturers to make clothing. Workers can make as little as 21 cents an hour, and according to labor organizers, shoddy wiring and locked gates are frequent at Bangladeshi clothing factories despite their highly flammable contents. Over the past five years, nearly 500 workers have died in a series of gruesome fires. Islam was last seen Wednesday evening outside the offices of BCWS, after having closed the office early because he believed the office was being monitored by Bangladeshi officials, according to information gathered by Nova. Two days later, a photo of Islam's body appeared in a Bangladeshi newspaper alongside a report about unidentified remains having been discovered. His wife recognized the photo. Islam's body bore signs of brutal torture, according to local police and to a statement issued jointly by two American groups, the Worker Rights Consortium and the International Labor Rights Forum. The release states that labor rights organizations in Bangladesh and the United States believe the killing is associated with Islam's work on behalf of apparel workers who sew garments for suppliers to major U.S. retailers and brands. One reason for their suspicions is that Islam had been previously detained and tortured in connection with his efforts on behalf of workers, according to Nova. Two years ago, Islam told his colleagues that he had been detained and beaten by Bangladeshi intelligence officials. He said the officials demanded that he write a letter implicating his colleagues at BCWS in instigating unruly labor protests that damaged some factory buildings. Islam refused, but told colleagues he had managed to escape his captors. Bangladesh Labor Organizers Concerned for Personal Safety One of those implicated in the protests was Kalpona Akter, the head of BCWS, who told ABC News in a recent interview that she was concerned that her group and others could face intimidation or even jail time if they continued to fight for safer working conditions and better pay in Bangladesh. In her interview, Akter told ABC News that she was willing to accept the risk involved in fighting for better working conditions. "I was the worker," she said. "I have experienced [working] 23 days in a row …I was sleeping in shop floor. I was taking sometime shower in toilets. I was drinking unsafe water. I have been slapped by the supervisor. So I don't want to see anymore workers go the same way." Nova told ABC News he believed that U.S. companies should use their leverage inside Bangladesh to improve conditions for workers. "For two years, labor rights groups have been calling on Wal-Mart and other companies that produce in Bangladesh to use their power to protect the BCWS staff, and other labor rights advocates, from the government's campaign of repression," said Nova. "Instead, they just increase their production in the country, which sends exactly the wrong message to the government and the factory owners."