The dead man, identified as Boris Salkovskiy, 66, was found by a Burmese worker who looked after the garden.
Mr Salkovskiy initially appeared to have hanged himself using a tow rope tied to a branch of a tree. But police noted that his feet were firmly on the ground and his knees were bent, possibly indicating that he had been murdered. An overturned chair lay close by, along with the victim's flip-flops.
A doctor, called to the scene, estimated the time of death at around 3 this morning.
The Russian entered Phuket on March 16 on a tourist visa and was due to leave again on April 13, but it is not yet clear whether he was staying at the villa or somewhere else close by.
Staff at the neighbouring Thai Style Restaurant & Bar said that they had seen him walking past in the mornings, “usually alone”.
Mr Salkovskiy’s body was taken to Patong Hospital for X-rays and other tests to establish the cause of death and to see whether he did in fact die of hanging.