Four suspects have been arrested in connection to the murder of a world-renowned ivory investigator who was killed at his home in Kenya.

Nairobi Police Chief Japheth Koome said the four were apprehended on Monday afternoon to help with investigations regarding the death of Esmond Bradley Martin.

"We have the four suspects in custody," Mr. Koome said. He however did not give further details as to their identities or suspected role.

Esmond Bradley Martin, one of the world's leading ivory trade investigators living in Kenya, was on Sunday found dead in his house at Langata, Nairobi.

The 75-year-old, who was alone in the Nairobi house, had a stab wound in the neck.

His wife, Chryssee Martin, said she found her husband's lifeless body after coming from a nature walk at around 4pm.

Ivory trade

Esmond has authored several ground-breaking investigative reports on rhino and ivory smuggling in Kenya and the trade in China, Vietnam, and Laos.

He was said to have been working on his latest report on the rhino and ivory trade by the time of his death.

The renowned ivory detective had been travelling around the world alongside his wife and colleagues in a bid to identify ivory and rhino markets, the traffickers and the modern-day uses.

Among his achievements was helping persuade China to shut down its legal rhino horn trade in 1993 and ivory trade last year.