Twenty-seven-year-old Edward Moran, 19-year-old Cristian Bravo and a 17-year-old teenager were arrested during "Operation Stray Bullet" a gang operation led by authorities last month.
They were arrested on separate charges from the murder, but the evidence surrounding the gang operation helped detectives make the arrest.
Tuesday they were arrested for Serna's murder.
Serna was shot in the chest on June 5th, 2019 while working in the front yard of his Cutler home.