The sisters were forced to hold up their hair in a bun before a teen fired a shot behind each of their heads.
Two twin sisters have been killed by a teen suspect while the gang-related execution was filmed on an Instagram live stream.
The 18-year-old victims, identified as Amália Alves and Amanda Alves, were found dead on the side of a road behind a housing complex in Pacajus, Ceará, last Wednesday morning, hours after they killed.
Video footage captured the twin teenage mothers kneeling next to each other on the dirt street.
Both apparently were forced to hold up their hair in a bun before Mateus Abreu, 17, fired a shot behind each of their heads.
While authorities have not provided a motive for the executions, newspaper Jornal de Brasília reported that the twin sisters were killed because they were aware of incidents involving local drug dealers.
Abreu then fired two more shots are one of the girls and and subsequently stood over the other victim and pumped four more bullets at her.
Neighborhood residents alerted the police after discovering the bodies at the location where they were assassinated.
Amanda Alves leaves behind a three-year-old daughter. Amália Alves was a mother to a six-month-old son.
Abreu was arrested by the Ceará Civil Police later Wednesday.