Acting Judge Boet Smit on Wednesday found Luvo Nketho and Yalezwa and Vuyisile Ndzumeka guilty of the attempted murder and murder of Sithembile Mathiso High School principal Bongani Dingana, the Cape Times reported.
He also found Nketho and Vuyisile Ndzumeka guilty of the murder of acting principal Mandisa Ndziba, who stepped in after Dingana's slaying.
She was killed two months after Dingana as she was asking questions about stolen money, according to the report.
The three took out funeral policies in Dingana's name in 2009, declaring themselves beneficiaries.
Nketho was hired to kill the principal, but failed in a first attempt on April 16, 2009. Two months later, Dingana was shot dead while walking home on crutches.
Smit also convicted the couple of fraud for the policies taken out.
Sentencing is expected on March 19.