An ex-police informant - one of four men accused of murdering an international steroid smuggler in Cape Town last year - is at risk of being assassinated because he has blown his cover, the Wynberg Magistrate’s Court has heard.Brothers Matthew and Sheldon Breet, along with co-accused Cheslin Adams and Fabian Cupido, appeared in the court on Monday in a case where shocking allegations about club security conflict - including how an explosive device was created and fitted under someone’s vehicle - have emerged.The control of nightclub security in the Western Cape has been the focus of several recent court cases.Sheldon Breet used to be a police informant and was also allegedly involved in several illicit trades, including steroids and rhino horn.He and his brother are applying for their release from custody. Adams and Cupido are not applying to be released on bail.Brian Wainstein, known as the international "Steroid King", was shot dead in his Constantia home either late on August 17, 2017, or early the next morning, while asleep alongside his girlfriend and child.READ: International 'Steroid King' shot dead in Cape Town home in possible hitAt the time of his murder, he was wanted in the United States for illegally importing anabolic steroids.Matthew and Sheldon Breet face charges of conspiracy to commit housebreaking with the intent to murder, as well as a charge of murder.'Gofers' versus key underworld playersThe State has alleged that the brothers worked for Wainstein, used their links to the 27s gang to facilitate his murder and were highly connected in the underworld.However, their advocate has countered that they were mere "gofers" to those involved in the underworld, and acted as bodyguards and ran errands for them.On Monday during the bail application, the State and defence teams submitted their heads of argument.Prosecutor Mervin Menigo’s argument was that Sheldon Breet had admitted to being involved in various offences before his arrest for the Wainstein murder.Police informant involved in illicit trades"[He] also admitted that the bulk of his income was derived from operating an illegal steroid business, assisting in dealing in illegal drugs, rhino horns and possible money laundering," it said."He counts being a police informer as another source of income. He concedes that he has not informed the police regarding the clients to whom he illegally sold steroids and this remains a potential source of illicit income."Sheldon Breet had previously indicated that, if he was released from custody, he would possibly take up an apprenticeship involving electrical installations.However, according to Menigo's argument, he did not have qualifications for this.Menigo said that, not only would the Breet brothers pose a risk to the public if they were released on bail, but that they themselves would be at risk.'Accused at risk of assassination'"The accused are at risk of assassination and anybody who may find themselves in [their] vicinity… The risk has been heightened by [Sheldon Breet], who has disclosed that he is a police informer on other matters," Menigo’s argued.It said that, at the time of his arrest, Sheldon Breet had pointed out a container in which "contraband, including unlicenced ammunition", was discovered.Matthew Breet had been arrested after surrendering himself and, at the time, Menigo argued, illegal firearms were in the boot of his vehicle.Menigo's argued that Matthew Breet had conceded that, before his arrest, he had operated a security company which had not been registered with the necessary authority as required by law.He said that Matthew Breet had a pending assault charge and, while released on a warning in relation to this, he had been "implicated in the possession of firearms which police have linked to a plot to perpetrate violence in the ongoing conflict between organised crime players in the club security industry".'Manufacture of an explosive'"He has been charged with the manufacture of an explosive which was placed under a motor vehicle of another person and the matter is pending," Menigo’s argument said.However, delivering his heads of argument on Monday, advocate Dirk Uijs SC, who was representing the Breet brothers, said the State had not provided details to back up allegations levelled against the brothers.He also hit back at the State's claim that the brothers were at risk of being assassinated."It seems to me they're far more likely to be assassinated in a South African jail," Uijs said.He said, as an informant, Sheldon Breet had actually been assisting the police by providing them with information and that perhaps his crime intelligence handler should have been heard in court.The State believed the brothers posed a flight risk and could commit crimes if released on bail.'They will not evade their trial'But Uijs said they planned to stand trial."There's no suggestion they could be smuggled out the country. The probability they'll evade trial is just about zero," he said.Uijs also insisted the State had no evidence to suggest there was a probability they would commit crime if released from custody.The Breet brothers are expected to hear whether or not they will be released on bail on June 29 when judgment in the application is set to be delivered in the Wynberg Magistrate's Court.