The murders of at least six LGBTQ men in Colombia’s second largest city since the beginning of the year have sparked concern among advocacy groups.

Hernán Macías López, 30, was found dead in the bathtub of a hotel room in downtown Medellín on March 30. El Espectador, a Colombian newspaper, reported authorities found Macías tied up with signs of strangulation.

Juan Danilo Bedoya Román’s mother on March 15 found him dead in his bedroom in their home in Las Estancias, a neighborhood in Medellín’s Comuna 8. Media reports indicateBedoya, 30, was partially undressed and his feet and hands were tied up when his mother discovered his body.

Sahmir Javier González Sarmiento’s friend on Feb. 15 found him dead in an apartment in Las Acacias, a neighborhood in Medellín’s Comuna 11. Authorities said the 28-year-old’s legs and hands were tied with a belt and a sheet.

EgoCity, an LGBTQ magazine, reported relatives on Jan. 27 found Juan David López Álzate’s body inside an apartment in Antonio Nariño, a neighborhood in Medellín’s Comuna 13. Other media reports indicate the 31-year-old was strangled with a belt and was found tied up.

A 36-year-old man who was attacked in downtown Medellín on Feb. 15 survived.

“The victim was stabbed,” reported EgoCity. “He recovered from his injuries after he was brought to a clinic.”

A source in Medellín on Monday told the Washington Blade authorities have described the murders as “isolated events.”

“They have the same pattern,” said the source. “One has to think that they are serial killings and in different neighborhoods in the city.”

Caribe Afirmativo, a Colombian LGBTQ rights group, on April 1 in a series of tweets noted it has confirmed six gay men have been killed in Medellín since the beginning of the year, and each of them “have similar circumstances.”

“It is important that authorities during the investigation do not revictimize the affected LGBTQ community and stigmatize the use of social media to meet and have encounters with other people,” said Caribe Afirmativo.