Cape Town High Court Judge Robert Henney has found Xolile Mngeni guilty of killing honeymoon tourist Anni Dewani.
Husband Shrien Dewani from Bristol is accused of masterminding the murder. He denies involvement.
Two other men are already behind bars after pleading guilty to the roles they played.
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Prosecutors say the group made at least 18 drug deliveries to Gloucester from the Midlands before being caught.
62-year-old Celia Hollingworth from Bradford on Avon was reported missing on Thursday.
Wiltshire Police say a member of the public contacted them after the body was found in a field off Cow Drove.