A gang armed with bows and arrows killed a British-born geologist in southeastern Kenya where he ran a mining firm, police said on Thursday.
Campbell Bridges, 75, was murdered while on his way back to the firm's headquarters late on Tuesday in Wundanyi area, Coast Province Criminal Investigation Department chief Reche Nyaga said.
Six people have been arrested.
"Some of those who have recorded statements have indicated that they know some of the attackers... We are also seeking to establish the motive," Nyaga said.
Bridges, who owned First Green Garnet Mining Company, discovered the Tsavorite gemstone, a shimmering green stone found around the border between Kenya and Tanzania and named after Kenya's vast Tsavo National Park.