Bheki Mlangeni was born on 28 December 1958 at Jabulani, Soweto Johannesburg, Transvaal (now Gauteng), and he was the fourth child of five children.

Mlangeni studied law at the University of Witwatersrand. He was detained for political activities in 1985 at Sun City (Diepkloof Prison, Johannesburg).

On 17 November 1989, prompted by the death row confessions of a police officer, Butana Almond Nofemela, former Security Police Captain Johannes Dirk Coetzee made his own revelations about his activities as the commander of a covert South African Police’s death squad. Following these confessions, former President F W de Klerk responded to public outcry by setting up the Harms Commission of Inquiry on 5 March 1990.

Coetzee gave key testimony to this Commission. In May 1990, a walkman cassette player with an explosive device in the headphones was sent to Coetzee in Zambia. The sender’s name was given as Bheki Mlangeni, with whom Coetzee had been in contact, and the return address was Mlangeni’s home in the Soweto, Johannesburg. Coetzee was suspicious of the parcel so refused to accept it. In February 1991, it was returned to the sender Bheki Mlangeni of the law firm Cheadle, Thompson and Haysom, Johannesburg. At the time, Mlangeni and his law firm were investigating the Apartheid’s government hit squads.

Mlangeni and his law firm had presented evidence in 1990 to the Harms Commission of inquiry into hit squads, which issued a report concluding that no proof existed that either the army or the police were involved in political assassinations. Coetzee, then in London, had been an important witness in the inquiry, and Mlangeni had been in frequent contact with him during that time.

Mlangeni's law firm said he had received an anonymous telephone call in April 1990, a month before the bomb parcel was first sent, warning that a hit squad had been dispatched to kill Coetzee in Zambia. It was not generally known at the time that Mlangeni was in contact with Coetzee and the firm suspected wiretaps were used to obtain that information.

Eugene de Kock, a former Commander of Vlakplaas tried to assassinate Coetzee in 1990 by sending him a letter bomb to him inLusaka, Zambia. de Kock used the name Bheki Mlangeni, as the "sender." Coetzee, suspicious of the parcel, refused to accept it and the parcel was returned by the Zambian postal services to the name of the sender on the parcel, Bheki Mlangeni.

Mlangeni, however, put on the booby-trapped headphones, turned on the tape and was blown up instantly in February 1991.

The African National Congress (ANC) said Mlangeni and Coetzee, then a member of the ANC in exile, had exposed the activities of both the Civil Cooperation Bureau, a secret army unit that carried out surveillance and attacks on anti-apartheid leaders, and "other assassination gangs in the employ of the Pretoria government."