Mwathi died from what has been described as a fall on February 22.
The circumstances leading to his death have remained a puzzle since. It had been hoped that the involvement of the country's top sleuths will unravel the puzzle and advise the Directorate of Public Prosecutions accordingly.
DCI chief Mohammed Amin on Wednesday night said investigations into the death of Mwathi are completed and the file handed over to DPP Noordin Haji.
Amin, through DCI's official Twitter handle, said the investigators had received an autopsy report from the government pathologist and the government chemist following completion of fresh investigations.
"The file is now completed and has been forwarded to the DPP for perusal and advice," Amin said.
Sources indicate pathologists did not find evidence that the victim was sodomised as had been claimed, which caused the need for a second examination of the body after exhumation in Nakuru county.
The DCI has recommended that the matter be dealt with as a public inquest after investigators found no evidence linking the five people who were last seen with Mwathi to his death.
Before his death, Mwathi, the DJ and his driver visited a popular entertainment joint on Thika Road where they spent more than five hours making merry. Save for the DJ's driver and a cousin who is also a guitarist, Fatxo, Mwathi and two women were on one table. The other man and a driver sat at a different table and did not take any alcohol.
At around 4.30am, Fatxo, Mwathi and two women left the bar and headed home. The driver and the guitarist followed them to the house.
By then, Mwathi and the other visitors continued partying. It's at this point that the two women requested Fatxo to escort them to their house, also in Roysambu.
According to the statements by the investigators, Fatxo left Mwathi in the house with his driver and the guitarist. He (Fatxo) directed the two men to lead Mwathi into a guest bedroom where he would spend his night.
The investigators say Fatxo did not return to the house as he had earlier indicated and that he only came back at around 9am. He found police officers from Kasarani police station in the compound.
He was told a man had fallen from the 10th floor of the building. It did not occur to Fatxo that the dead man was Mwathi.
When he arrived at his house, Fatxo proceeded to his bedroom to sleep . He also enquired from the two men who were in the house where Mwathi was. He was informed that he was sleeping in the guest bedroom.
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All along, neither Fatxo nor the two men who were in the same house as Mwathi was aware that Mwathi was dead.
At around 2pm, Fatxo woke up and freshened up ready to leave. He then proceeded to the guest bedroom where some of his clothes were. He checked around but did not find Mwathi.
He asked the driver and the guitarist if they had seen Mwathi leave. The two who were sleeping in the sitting room said they had not seen Mwathi leave the house.
While in the bedroom, Fatxo said he noticed the curtains in the room had been removed. It's at this point that it dawned on him that the dead man was Mwathi.
Police in their report say Fatxo and the two men left the house immediately and proceeded to Kasarani police station to report the matter.