Businessperson Shrien Dewani has been acquitted of the murder of his wife Anni while on honeymoon in Cape Town in 2010.
State prosecutor Adrian Mopp says were it not for the killing of Anni Dewani, the organisation of the entire plot by the hitmen would be "comical".
The police want to know why a mystery donor or foreign human rights group would fund the large legal costs of a man who had chosen a life of crime.
Xolile Mngeni, who was diagnosed with a brain tumour, has passed on "while the monitoring of his medical condition was underway", say officials.
Murder-accused Shrien Dewani's defence says it was Mziwamadoda Qwabe who pulled the trigger that killed Anni, and not Xolile Mngeni.
The Western Cape High Court has sentenced Xolile Mngeni to life for killing tourist Anni Dewani, who was on her honeymoon in South Africa.
Only after the judge considers his medical condition, will a sentence be handed down to Xolile Mngeni for the death of Anni Dewani.
Questions have been raised about who is funding the lawyer representing the man accused of pulling the trigger in Anni Dewani's murder.
Mziwamadoda Qwabe has been sentenced by the Western Cape High Court to 25 years imprisonment for kidnapping and murdering honeymooner Anni Dewani.
Two men charged with the township murder of British honeymooner Anni Dewani are to go on trial next year in the Western Cape High Court.
Xolile Mngeni, awaiting trial for the alleged murder of Anni Dewani, was still receiving treatment in prison for a malignant brain tumour.
Xolile Mngeni, one of the two men in police custody for the murder of Anni Dewani, has had surgery to remove a brain tumour, a court has been told.
A probe is under way into a security lapse around the alleged hitman in the Dewani murder, who was seen in hospital, unshackled with only one guard.
A UK court ruled Shrien Dewani can stay home for at least another two weeks following an application by SA to have his bail revoked.
When police arrested Xolile Mngeni for the murder of Swedish newlywed Anni Dewani in Cape Town in November, he was already a wanted man.
Closed circuit television video and damning text messages make up a mounting pile of evidence against Shrien Dewani.
The trial of three men arrested for the murder of honeymooning tourist Anni Dewani will resume in Cape Town on Monday
A second suspect has been arrested in connection with the hijacking and murder of a tourist in Gugulethu at the weekend.