A South African businessman pleaded guilty to corruption charges and offered to provide evidence against “high-ranking officials,” underscoring the breadth of a huge graft probe in the continent’s biggest economy.

Vusimuzi Matlala entered the plea over a $12.5 million police healthcare tender-rigging case, admitting to bribing officials to secure a medical screening contract for which his company lacked adequate facilities.

The deal has not yet been accepted by magistrates, but comes amid growing questions over law and order in South Africa: A national commission is investigating whether criminal syndicates have in effect taken over law enforcement, with a minister having been suspended and a top official facing criminal charges; at the same time, the country’s president is under pressure over an impeachment inquiry into the theft of undeclared cash at his property.