Two men shot Mrs Root, 69, in her bed after breaking the window and firing an AK-47 assault rifle at close range. She tried to staunch her bleeding with bedsheets, but died from loss of blood.
"These people never entered the house," Simon Kiragu, the Naivasha police chief, said. "They looked through every window until they identified the room in which she was sleeping - she kept a spotlight outside - and shot her."
Mr Kiragu said a tracker dog picked up a scent from the crime scene and followed it to the two men's home. One of the men was described as a welder while the other was a teacher at a nearby school.As investigators continue the hunt for the murder weapon, police raided the nearby Karagita slums, detaining 21 people for questioning.
Wildlife film-makers and conservationists paid tribute to Mrs Root's passion for wildlife conservation, which some say may have led to her death.
There is speculation that Mrs Root may have been targeted over her efforts to stop illegal fishing in the Rift Valley lake, where a growing population has increasingly turned to fishing to feed themselves, bringing conflict with conservationists.
Mrs Root collaborated with former husband Alan to make several popular films about African wildlife, including Balloon Safari and Two in the Bush. Vicky Stone, a film-maker, praised her friend's work. "She made inspiring and groundbreaking wildlife films with Alan and together they created some of the best natural history documentaries ever made."
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