#SCOOBYDOO The Seocho Water Mystery

Can you figure this mystery out?

On Oct 19, in Seocho, Seoul two employees of a company to be named, lost consciousness after coworkers say they drank out of a water bottle. When journalists arrived to the scene coworkers and others working at the 5 story office building seemed hesitant to speak. The two employees that lost consciousness were rushed to the hospital where only one of the two recovered enough to be sent home. Think this is just a prank gone bad? Well then comes news that an Employee C that was at the scene when it took place was found dead. Police say there are no signs of foul play and leaning towards suicide as the cause. HMM What do you think happened?