Kisii Teaching and Referral Hospital medical intern Vincent Bosire Nyambunde, whose body and that of a woman were found in a flat in Nyamataro area of Kisii town, had called his relatives moments before his death.
Bosire's relatives told journalists at their home in Rigoma, in neighbouring Nyamira County, that he had called his mother to tell her that he had been assigned to work in the Intensive Care Unit (ICU).
But the family members said they were surprised when Mr Bosire told them that they would be informed if anything happened to him.
"Before he disappeared, he called our mother around 7pm on Wednesday and told her that he was working in the ICU. But we were startled when he said that if anything happened to him, we would be informed. I wondered what he meant by that statement and went to tell our mother that something had gone wrong somewhere," said Mr Bosire's sister.
The deceased's uncle, Charles Siro, said they were looking forward to the results of a post-mortem on Mr Bosire's body to find out what could have caused his death and that of his 'lover'.
"We cannot say with certainty that they died where their bodies were found, we don't know what happened in that house. We will have to wait and see what the post-mortem report says," said Mr Siro.
Bosire's elder brother, Simon Nyambunde, said they had been informed that his sibling had not reported for work for a few days and that his phone had been switched off.
He said they went to his house to check on him after he went missing but found the house locked from the inside.
They alerted the police who helped them access the house by breaking the door. Upon entering the house, they stumbled on the two bodies lying on a mattress on the floor.
Mr Bosire and his alleged girlfriend Angela Mora, who had reportedly returned to the country from the US a few days earlier, were holding hands. They were both lying on their backs, fully dressed in sweatpants and covered with separate duvet covers.
Medical syringes and needles were scattered on a maroon three-seater sofa next to where the bodies were found.
Kisii County Police Commander Charles Kases said the matter had been taken up by DCI officers to establish how the two lovers met their deaths.
"It is an incident that has shocked many people in the neighbourhood but we believe we will establish the truth as soon as possible," Mr Kases said.