The bodies of Norman and Rita Joel, of Leigh-on-Sea in Essex, were found dumped in the village of Mwakirunge, 16km from Mombasa. An autopsy revealed that both Mr Joel, 70, and his wife, 67, died from multiple stab wounds.
Both Mr and Mrs Joel had been frequent visitors to Kenya for nearly 20 years, owned a home in the country and were known to have given money to local communities.
A Foreign Office spokesman said the British High Commission was made aware of the deaths on 15 October, but could not confirm when the murders took place. According to Kenyan Police, the retired couple were killed a day after arriving in the country.
Mr Kiraithe declined to comment on reports that the couple had died during a botched robbery, but said: "When visitors arrive like this and do some charity work, people might imagine they had some cash on them."