Dr Ben Samphire was described as a "very talented young man"
A coroner recorded a verdict of unlawful killing on a conservationist who was shot dead in South America.
Ben Samphire, 31, of Bristol, was studying a rare monkey species in Ecuador when he was shot in the back.
The inquest at Newport, south Wales, was told the main suspect had not been found and local police had refused to pass on the name to British officers.
Gwent Police said it would continue its inquiries, together with the Foreign Office, into the killing.
The inquest heard there was no obvious motive despite earlier reports that he had been mistaken for an intruder by a landowner.
Det Sgt Wendy Keepin told the hearing: "They have told us they have been making inquiries to locate the offender.
"The village he is located in is in a forest and they believe he has gone to ground.
"They are struggling to locate him."
Dr Samphire was leading a project to study monkeys near a village on the Pacific coast of Ecuador when he was shot in February last year.
He was just weeks into his trip.
Mr Samphire's mother Elizabeth Samphire, 65, of Abergavenny, told the hearing her son had a passion for primate conservation and was a leader in his field.
She said her son, who was born in Zambia but lived in Bristol, had kept in touch with her via email, telephone and postcards while he was away and had never expressed any fears over his safety.
Deputy Gwent coroner Wendy James said: "He was a leader in his field and obviously a very talented young man.
"Ben had a passion for primate conservation which meant he travelled to Ecuador to take part in a research project.
"After being in Ecuador a matter of weeks Ben was shot in the back, sustaining fatal injuries.
"The motive for this attack has not been communicated by the Ecuador police.
"I sincerely hope police in Ecuador persevere with their inquiry to detain the perpetrator as soon as possible."
She recorded a verdict of unlawful killing caused by a shotgun wound to the back.
Dr Samphire completed a degree at the University of Sheffield, and an MSc in cognitive evolution at the University of Reading.
He also received a doctorate from the Institute of Archaeology, University College London, and was planning to take a master's degree in primate conservation.
After the inquest, Det Ch Insp Russ Tiley said: "The family are satisfied with the verdict. The circumstances of Ben's death were tragic and still we don't know why he was killed.
"Gwent Police will continue our inquiries in conjunction with the Foreign Office to establish why Ben was killed and who was responsible."