A second monarch butterfly activist has been found dead in Mexico. The man, who is believed to have been murdered, was found in the same butterfly preserve where another activist was found dead just days before. 

Raúl Hernández Romero was found on February 1 inside a monarch butterfly sanctuary in the municipality of Ocampo, The Associated Press reports. His body showed signs of a beating, and had a knife-type wound to the head.

The body of Homero Gómez González was found in a well on January 29. Officials haven't determined the circumstances of his death, but autopsies show he also suffered a head wound before drowning in the well.

Both men worked to protect the monarch butterflies' winter habitat in Mexico. Hernández worked as a butterfly tour guide in Michoacán; Gómez opened a butterfly sanctuary in the same state in November, as part of a strategy to stop illegal logging in the area, the BBC reports. 

According to his family, Gómez had received threats prior to his death. 

Mexico saw its highest murder rate ever in 2019, according to BBC News. Many of the murders are believed to be the work of gangs carrying out criminal activity — such as logging in protected habitats — that will kill anyone who poses a threat to those operations. 

The butterflies migrate south every year through Canada and the United States to mountains in the Mexican state of Michoacan, where the insects winter, clumped to oyamel pine trees. Monarchs return to the same sites — and sometimes even the same trees — each year.

Tens of thousands of the striking orange and black insects can be seen on a single tree, clustering together to stay warm. The colorful spectacle has become a draw for tourists, and has created a tour guide industry in the impoverished mountainous region. 

The annual migration, however, is threatened by logging, as well as avocado farming, pesticide use, and climate and environmental change. The monarch has been pushed to the brink of extinction by habitat loss and pesticide use, Tierra Curry, a senior scientist with the Center for Biological Diversity, told CBS News last March.

According to Xerces Society, a non-profit environmental organization focusing on invertebrate conservation, the monarch population during the 2018-19 winter was at an all-time low, and this year's numbers did not show improvement.