FORMER National Party cabinet minister and convicted fraudster Pietie du Plessis died of a heart attack in Pretoria on Wednesday morning, his friend and former cabinet colleague Pik Botha said. Although Du Plessis served three years of a nine-year prison term in Pretoria Central Prison for company fraud, he always retained his self-esteem and respect, Botha said. Du Plessis held several cabinet portfolios including minister of manpower.