Following the Monday charging of three suspects involved in the chemical dumping at the Sungai Kim Kim in Pasir Gudang, Malaysia, it was revealed that authorities are still in search of a fourth suspect who may have been involved in the case.

According to The Straits Times, Johor Police Chief Datuk Mohd Khalil Kader Mohd was quoted as saying police are still in search of another Singaporean suspect who may have knowledge about the incident that disrupted the lives of many Malaysians.

Datuk Mohd Khalil reportedly said the suspect is believed to be in his 30s, a businessman, and could hold evidence that will help authorities come to the bottom of the probe. He also said state police will continue to cooperate with Singaporean authorities in hopes of taking the suspect under appropriate custody.

"We are tracking down the man and will be conducting further investigation in this case. We understand that three men, including a Singaporean, were charged in court today," Datuk Mohd Khalil reportedly said during a media briefing on Sunday.

Cleaning of the polluted 1.5-kilometer stretch was completed last week, Malaysian authorities confirmed. 1,250 tonnes of soil, sludge, and water were removed from the area to ensure that no chemicals are still present.

Shortly after the chemical spill, over 100 schools closed down in the Pasir Gudang region to prevent students and parents from potentially contracting diseases after inhaling the chemicals. Many residents were forced to evacuate as for health-related concerns.

While the fourth suspect is still at large, multiple outlets confirmed that the three suspects will face more charges as the investigation ensues. According to Channel News Asia, the two directors who have received 15 charges over the Pasir Gudang chemical spill pleaded not guilty.

Malaysian Yap Yoke Liang and Singaporean Wang Jin Chao pleaded not guilty to allegations of failing to conduct necessary monitoring of manufacturing processes. They also pleaded not guilty to failure of informing appropriate authorities about scheduled waste generation within the given timeframe of 30 days.

The third suspect, N Maridass, is a lorry driver who is said to have been an accomplice in the disposal of the chemical waste into the Sungai Kim Kim earlier in March. The crime was reportedly laid out without the approval of the Director-General of Environmental Quality.

Maridass and Yap have been allowed to post bail of RM100,000 and RM 250,000 respectively but Wang was denied of his plea to bail. The case is scheduled for hearing on April 30.