Andrew Loveridge from the Department of Zoology at Oxford University, which has a team supplying and fixing collars that monitor the lions in the Hwange National Park, said: "I fitted it last October. It was monitored almost daily and we were aware that Xanda and his pride was spending a lot of time out of the park in the past six months, but there is not much we can do about that.
"Richard Cooke is one of the 'good' guys. He is ethical and he returned the collar and communicated what had happened. His hunt was legal and Xanda was over 6 years old so it is all within the stipulated regulations."
Loveridge said he hoped that there would soon be a 5km exclusion zone around the Hwange National Park so hunters would no longer accidentally shoot collared lions that wander outside the park.
Cecil the Lion had wandered outside of the park to the area of his birth, close to the boundary.
Cooke, a well-known professional hunter who lives in Victoria Falls, did not answer his phones on Thursday and has not yet revealed the name of his client. But most lion shooters are from the US, UK, Germany or South Africa.
The client may have paid about £40,000 ($70,000) for the shoot and for Xanda's head to be cured and mounted and sent to him wherever he lives.
Cecil's death on July 1, 2015, caused global outrage and threw a spotlight on trophy hunting in Africa.
The Daily Telegraph in the UK broke the news that Walter James Palmer, a 55-year-old dentist from Minnesota, US, had paid US$65,000 (about $88,000 at today's exchange rate) to shoot and kill the much-loved lion with a bow and arrow.
He was forced to abandon his practice in suburban Minneapolis for weeks amid an international outcry over his actions.
Conservation groups in Zimbabwe and around the world reacted angrily too - partly because the Cecil was known to visitors and seemingly enjoyed human contact, and partly because of the way in which he was killed.
The 13-year-old big cat was shot at night near his birth place, close to the national park. He didn't die immediately and was tracked down the following day and finished off.
His head was curing in Bulawayo in preparation to be dried and mounted when police seized it. Charges against Palmer were later withdrawn.
After the shooting, many US hunters cancelled trips to Zimbabwe as the massive level of negative media coverage dominated headlines for weeks.
However, some have begun returning to Zimbabwe as the US ban on the importation of trophies has been lifted.
More then 70 per cent of funds to safeguard Zimbabwe's wildlife and catch poachers comes from revenue from professional hunters.
