South Korean authorities are moving to formally arrest 58 of the 64 citizens recently repatriated from Cambodia over alleged involvement in online scam operations, police said Monday.

The 64 South Koreans, detained in Cambodia over several months, were flown home on a charter flight Saturday. Upon arrival, they were held while investigators assessed whether they had joined the scam organizations voluntarily or were coerced.

Online scams, particularly in Southeast Asia, have surged since the COVID-19 pandemic, victimizing both those forced to work in scam operations and the targets of fraud. Criminal networks reportedly earn billions annually from such schemes.

State prosecutors have requested arrest warrants for 58 of the returnees, accused of crimes including romantic scams, fake investment schemes, and voice phishing targeting fellow South Koreans. Courts are expected to rule on the warrants in the coming days. Five individuals have been released, though authorities have not disclosed the reasons.

Police said four returnees reported being beaten in Cambodian scam centers against their will. Public concern has grown after a 22-year-old South Korean university student was found dead in Cambodia in August, allegedly tortured after being lured to provide his bank account for scam operations.

United Nations and other estimates suggest over 100,000 people are trafficked to scam centers in Cambodia, with large numbers in Myanmar and other countries. South Korean officials estimate about 1,000 of their citizens remain in Cambodian centers and recently imposed travel restrictions on parts of the country while sending a delegation to discuss joint countermeasures.

Interpol reports indicate that in the past three years, scam victims have been trafficked from South America, Western Europe, and Eastern Africa to Southeast Asia, with new scam centers emerging in the Middle East, West Africa, and Central America.