Three Mexican film students kidnapped last month were tortured, killed and dissolved in acid according to local officials in the Western state of Jalisco.
The Jalisco New Generation Cartel is believed to be behind the killings having confused the male students, all in their 20s, with rival gang members.
The case drew protests around the country, with people demanding justice and an end to the violence crippling Mexico in recent years.
The news came within 24 hours of a breakthrough in another high-profile case with police arresting a man allegedly involved in the murder of the award winning journalist Javier Valdez last year.
"Yesterday, we arrested in Tijuana, Baja California, 26-year-old Heriberto "N," who was identified as the alleged murderer of the journalist Javier Valdez Cardenas, who was killed on May 15, 2017 in Culiacan, Sinaloa," said National Security Commissioner Renato Sales at a press conference on Tuesday.
Valdez was known for his reporting on the drug trade in Mexico, which remains one of the world's most dangerous countries in for reporters. This year at least three journalists have been killed in the country while there were 12 cases last year.
More than 25,000 people were murdered last year in Mexico. Homicides hit their highest level in records going back 20 years.