The brother of Thembisile Yende - the Eskom employee who was murdered in May 2017 - died on Wednesday, Times Live reported. Mboneni Yende had been at the forefront of attempts to bring his sister's killer to book. Thembisile, a 29-year-old mother of one, went missing on May 17, 2017, News24 reported. Her body was found in her office at the isolated Eskom Pietersboth substation in Springs about 36km outside of Johannesburg. This was after Eskom workers detected a bad smell more than a week after she was reported missing.Thembisile's lover and colleague, David Ngwenya, was arrested on June 15 the same year but charges against him have since been withdrawn.Read: 3 people were present when Thembisile Yende was murderedNgwenya, a 43-year-old technician at Eskom at the time, was accused of injecting Thembisile with a substance before striking her on the head with a crowbar and subsequently suffocating and strangling her after a struggle.He allegedly killed her after he suspected that she would "spill the beans" on his alleged involvement in a copper cable theft syndicate.According to Times Live, Mboneni died in hospital after an operation on Wednesday.A family spokesperson told Times Live Mboneni had been diagnosed with gastritis late in 2018.Brian Sithole told that publication Mboneni died in hospital around 00:00. "He was admitted two weeks ago for an operation."He reportedly said Mboneni's death was a blow to the Yende family, who was still seeking justice for Thembisile's death.