Switzerland’s top prosecutor opened a criminal probe against “unknown perpetrators” suspected of bribing foreign officials after a public interest group filed a complaint in 2017 against Glencore, adding to international scrutiny of the world’s biggest commodity trader. The investigation opened earlier this month relates to raw materials, and isn’t focused on the Baar, Switzerland-based company or a specific person, the Office of the Attorney General said in an email, declining to give further information. The original complaint came from Public Eye, a non-governmental organisation.