Gemballa was murdered shortly after arriving in Johannesburg in 2010. His body was found eight months later with a plastic bag over his head.
The Star reported that investigators had pinned two other murders on Krejcir - that of Sam Issa in Bedfordview in October last year and Zimbabwean Phumlani Ncube who worked for the Czech fugitive as a debt collector.
The newspaper said that sources close to the investigation said Issa and Ncube were murdered with the same stolen police rifle.
It was also likely that Krejcir would face further charges later this year, including money laundering and drug trafficking, investigator Paul O’Sullivan said.
Krejcir was denied bail in the South Gauteng High Court on Tuesday, Sapa reported.
He brought another bail application on an urgent basis after his previous attempt was denied by the same court in January.
Krejcir then launched another application based on "new facts" with the Palm Ridge Regional Court, which denied him bail again in February.
This was Krejcir's fourth attempt at securing bail since his arrest in November last year.
He is currently facing charges of dealing in drugs, attempted murder and kidnapping together with Desai Luphondo, Samuel Modise Maropeng, George Jeff Nthoroane, Jan Lefu Mofokeng and Siboniso Miya.
Luphondo, Maropeng, Nthoroane and Mofokeng were all released on R5 000 bail in December.
Miya is still in custody.