Joan Wells Root, 69, the daughter of a colonial-era British settler, was shot three times in her bed at her residence near the town of Naivasha, about 90 kilometers (55 miles) northwest of Nairobi, where she was raised and had lived for many years promoting environmental causes, they said.

Naivasha police commander Simon Kiragu said a guard had seen two gunmen breaking into the home on the shores of Lake Naivasha around 1:00 amThursday) where Root lived alone.

While burglaries are a frequent in the area, Kiragu said nothing had been stolen and that the motive for the killing was not yet known.

"Nothing was stolen from the house, the thugs just shot the deceased and left," he told reporters, adding that a major investigation had been launched and that sniffer dogs had been dispatched in a bid to find the perpetrators.

Rift Valley Provincial police chief Everet Wasige said investigators were trying to determine whether "it was a robbery attempt gone sour."

Kiragu said police had recovered seven AK-47 shell casings at the scene and that Root had been shot twice in the leg and once in the hip area and had bled to death as she crawled to her bathroom. He said police were questioning the guard and Root's other household staff.

Root, the daughter of Edmund Thorpe, a coffee farmer and photo safari guide who moved to Kenya in 1929, was well-known in Naivasha for her conservation efforts and kept several species of animals, including waterbucks, dik diks and birds, on her compound where hippos were known to gather, residents said.

With her ex-husband, Alan, she made several acclaimed films in the 1960s, 70s and 80s documenting Kenya's stunning wildlife and landscape, and had been active in trying to preserve Lake Naivasha, the Rift Valley's only freshwater lake.

Naivasha has been rife with animosity between foreign investors, mainly flower farmers, and the local population over access to resources, and has been the scene of violent attacks on European residents, although Root's murder is the first in several months.

At least three other Europeans have been slain in violent robberies in the Rift Valley since September 2004, prompting great unease and major security fears in the community.

Amid the heightened security concerns, a prominent British aristocrat, Thomas Cholmondeley, son of the 5th Baron Delamere, shot and killed an undercover game warden on his Rift Valley ranch but escaped a murder trial, insisting he acted in self-defense.

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