Updated

Thailand's national police chief says that a powerful local mayor was arrested and more than 50 police officers are under investigation in the country's widening human-trafficking scandal.

Police chief Gen. Somyot Poompanmoung said Friday that the mayor of Padang Besar was a "key suspect" in the investigation that began a week ago when dozens of bodies were exhumed from a jungle camp in the mountains of his constituency.

Somyot vowed that "heads will roll" in the police force, adding that police had been warned not to get involved in trafficking "but you didn't listen."

Somyot's comments marked the strongest admission yet of police involvement in trafficking syndicates that use Thailand as a regional transit hub and hold migrants in jungle camps while extorting ransom from their families.