BANGKOK: Thai authorities on Tuesday officially ended the search operation at the building under construction in the capital, Bangkok, that collapsed following an earthquake that killed dozens over a month ago.The 7.7 magnitude quake on March 28 centred in Myanmar, more than 800 miles (1,200 kilometres) away, killed at least 96 people in Bangkok, mostly at the collapsed site. More than 3,000 were killed in Myanmar.Eighty-nine bodies have been retrieved from the rubble while seven people remain unaccounted for at the site, officials said. They said they would continue to test hundreds of pieces of human remains to identify those still missing. The collapse sparked questions about the enforcement of construction safety and corruption. The high-rise building, meant to be the new office of the State Audit Office, was the only building that suffered a total collapse that day. The police on Tuesday said they are still investigating and will continue to collect evidence from the collapse site until the end of this month. Authorities are probing several companies and individuals for any wrongdoing in relation to the collapse, including the state-run Chinese contractor, China Railway No. 10 Engineering Group. The investigation has led to the arrest of its Chinese executive in Thailand, identified as Zhang, and three Thai shareholders on suspicion of operating the business through the use of nominees. Foreigners can operate a business in Thailand, but it must be a joint venture with a Thai partner, and they cannot own more than 49 per cent to protect local competitiveness. Another Thai-Chinese company, Xin Ke Yuan Steel, also came under scrutiny over the quality of the steel rods provided for the building. Industry Minister Akanat Promphan said two types of steel rods found at the collapse site did not pass safety standards and that Xin Ke Yuan supplied both. The company has denied any wrongdoing.