Mexican authorities said on Saturday they are investigating the possible murder of a tour guide working at a famous butterfly reserve in the western state of Michoacan, just two days after its former environmental activist was buried.

Raul Hernandez¡¯s body was found in the area in the early hours of Saturday, with different parts beaten, and a head injury possibly caused by a sharp object, the state attorney general said.

Earlier in the week, Mexicans in El Rosario mourned the death of activist Homero Gomez Gonzalez, who had fought for a decade to protect the monarch butterflies until his mysterious death. It is unclear whether the two cases are connected.

The sudden disappearance of such a high-profile campaigner had sparked an outcry in Mexico, an increasingly violent country where activists are routinely threatened, harmed or even killed as a result of their work.

Millions of the orange and black insects make a journey each year from Canada to winter in central Mexico¡¯s warmer weather. However, they are facing new challenges linked to extreme weather and changing habitat.

Michoacan state is not only home to the country¡¯s largest monarch butterfly reserve, a World Heritage Site, but also rival drug gangs who battle to control smuggling routes through often-arid terrain to the Pacific and the interior of the country.