On Monday, a Nepali army team located the wreckage of the helicopter, which crashed on Saturday. All 24 passengers died, including Mustonen, interim charge d'affaires at the Finnish Embassy in Kathmandu.
The 49-year-old Mustonen had served as a diplomat in Vietnam and Peru, and also worked as a forestry expert with the UN's Food & Agriculture Organisation (FAO).
Others on board included Nepal's junior forest minister, Gopal Rai, and his wife, as well as seven senior WWF officials from Australia, Britain, Canada, the US and an official from the US Agency for International Development.
Other passengers were conservationists working for the WWF and two Nepali journalists. The passengers had attended the handover of a WWF project to the local community and were on their way back.
The Russian-made helicopter was crewed by two Russians and two Nepalis.
The helicopter was found at the bottom of a deep gorge two kilometres from where it took off, some 500 kilometres east of the capital. The rugged area, located above 3,500 metres, is very remote with few villages. Therefore local officials say recovering and repatriating the bodies will be a slow, difficult process. YLE24, Reuters, AFP