Cape Town – Hawks investigators have discovered explosives at a location linked to a suspect who was arrested a few days ago in connection with the murder of Brian Wainstein, also known as the international "Steroid King".Brothers Matthew and Sheldon Breet were arrested on Saturday in connection with the killing. It was the second time Matthew had been arrested in four months.Explosives, ammunition, SANDF radios discoveredOn Tuesday evening Western Cape Hawks spokesperson Captain Lloyd Ramovha said that during a search at a location linked to Matthew, items including explosives were discovered.It is understood the explosives were discovered in a storage facility in Kraaifontein, while a firearm and ammunition were seized at a residential address.Ramovha said two South African National Defence Force radios were also confiscated during the operation.For a detailed breakdown of underworld activities in the Western Cape see News24's Underworld Unmasked showcase here.The Breet brothers appeared in the Wynberg Magistrate's Court on Monday.They are expected back in the court on Wednesday and more charges are expected to be added against Matthew.This will be in addition to the charges relating to Wainstein's killing.Wainstein was killed shortly after midnight on August 18 in what appeared to be a targeted hit in his home.READ: International 'Steroid King' shot dead in Cape Town home in possible hitHe was murdered while in the same room with his wife and child. Neither of them were wounded in the attack.In October, Fabian Cupido, 39, was arrested in connection with Wainstein's murder.This after he was detained following an alleged attempted attack at the Cape Town hospital where alleged Sexy Boys gang leader Jerome "Donkie" Booysen was admitted following an attack at Cape Town International Airport.READ: 'Fight' at hospital where wounded Jerome 'Donkie' Booysen is admittedSources with close knowledge of the matter said at the time that the suspect was dressed as a woman and had targeted another man with close ties to Booysen outside the hospital. One source insisted the incident was an attempted hit on the man linked to Booysen.Booysen was wounded at the Cape Town International Airport on October 18. A second man was also wounded in this shooting.Matthew was initially arrested in August for allegedly being in possession of prohibited firearms and ammunition. His arrest was said to be linked to the discovery of an abandoned luxury Jeep parked at a fast food outlet in Sea Point in April, in which two guns, ammunition and tactical jackets were.At the time Ramovha said Matthew had been a person of interest after an enquiry docket was registered during April 2017.READ: Hawks nab suspect after guns, bullet proof jacket and blue light seizedThis docket, News24 understands, had to do with an operation conducted that month.During that incident, members of the Hawks' firearms bureau unit, crime intelligence and police had reacted on information about a "suspicious group" that was gathered near a well-known food chain store in Sea Point.News24 understands that based on information from other sources, this gathering had to do with a grouping planning to intimidate club owners in the city centre and surrounds.