A Thai court's examination of 500 witnesses in a case against 88 suspected human traffickers will take as long as two years, a court official said on Tuesday, meaning verdicts in a case that sparked an international outcry are even further away. The defendants, including a senior general, were brought before a Bangkok court on Tuesday for examination of evidence and witnesses following a crackdown on Thailand's lucrative smuggling syndicates. "There are 500 witnesses in this case. Altogether it will take around 200 meetings to review witnesses which means examination will take two years," a court official said. The investigation and arrests followed the discovery in May of 30 bodies in a grave near a human trafficking camp on a hillside deep in a jungle near the Thailand-Malaysia border, which sparked an international outcry. However, some rights groups have questioned Thailand's commitment to end the illegal trade following the resignation on the weekend of a senior policeman in the investigation. Major General Paween Pongsirin, whose team led many of the arrests, said on Monday an order to transfer him to Thailand's south would expose him to revenge by members of trafficking syndicates still at large. Paween said he would disband his unit, raising concerns about protection for police officers. "I am truly sorry about this," Paween said outside the court. "I still want to be a policeman and be useful to society." Earlier, another court official said the examination of witnesses was expected to take just four days, but this would next to impossible given the number involved. Sunai Phasuk, Thailand researcher at Human Rights Watch, said examination of witnesses in the case could take more than two years. "One thing is clear, this will be a drawn-out trial and witnesses must feel safe and protected," Sunai said. "These are just some traffickers. There needs to be a follow-up investigation of others." Illegal migrants, many of them Rohingya Muslims from eastern Myanmar and Bangladesh facing religious and ethnic persecution, often brave dangerous journeys by sea to reach Malaysia and Thailand. The migrants are often held for ransom in squalid detention camps and according to some accounts face torture and starvation. The 88 suspects, who were brought to Bangkok in two buses, include two men who police have said are among the kingpins. Despite the police crackdown, the US kept Thailand for a second year on Tier 3 — the lowest tier — in its annual Trafficking in Persons report in July for failing to comply with the minimum US standards for the elimination of trafficking.