Prosecutors have raided the offices of Reckitt Benckiser's Korea unit as part of their investigation into hazardous humidifier sterilizers.
Investigators from the Seoul Central District Prosecutors' Office said Friday that they recently raided six places including the office in Yeouido, central Seoul, and Reckitt Benckiser's lab in Songdo, Incheon.
They also raided Lotte Mart headquarters in southern Seoul, which sold privately branded sterilizers. They confiscated documents and computer files to prove their alleged negligence.
The companies are suspected of having produced and sold the sterilizers containing harmful chemicals from April 2006 to February 2011.
It is believed that 142 people, many of whom were children and pregnant women, were killed using the products.
Prosecutors are looking into whether the firms conduct proper safety tests for the sterilizers and if they let the products be sold knowing that the chemicals used were deadly.
It took three years for the prosecution to begin the investigation.
Some victims and their families filed complaints with the prosecution against the sterilizer makers in August 2012. The prosecution has had police in southern Seoul look into the case, doing little until last month when police asked prosecutors to indict eight companies on charges of negligence and homicide.
"We're glad to hear the prosecution's investigation has begun. But, we're sad because it took so long for it to happen," said a member of the Asian Citizen's Center for Environment and Health, an NGO which represents the victims and their families.
In 2012, the Free Trade Commission found Reckitt Benckiser ran a false advertisement saying their products were safe for humans.
Last year, the Korea Centers for Disease Control and Prevention concluded that chemicals in the sterilizers were the direct cause of the deaths. A special law to take care of the victims was also established last year.
The British company has refused to admit wrongdoing, although it donated 5 million pounds to the Ministry of Environment to support the victims.
Some of the victims and their families flew to the company's headquarters in the United Kingdom in May to protest. They met with company representatives, but were told to talk with representatives of the Korean office. Some of the victims sued the British company in a U.K. court.
Some families also sought the Korean government's compensation, but a local court ruled earlier this year that the government was not responsible for the sales of the products.