Macedo is the fifth person to be sentenced in the September 2007 attack that killed Luis Garcia and wounded Francisco Clemente, a street vendor.
Prosecutors allege that Macedo shot Clemente four times because the vendor refused to pay a weekly "rent" to gang members for working on their turf. The baby, who was next to Clemente, was shot once in the chest.
In addition to Macedo, two other gang members, Juan Pablo Murillo and Guadalupe Torres-Rangel, were sentenced to life in prison Aug. 13 for first-degree murder.
Also, two others, David Gonzalez and Ralph Santiago, were sentenced in July to 11 years and 13 years in prison, respectively.
A sixth man, Yovanni Velasquez, awaits a Sept. 24 sentencing. Police say Velasquez acted as a lookout and helped to dispose of the murder weapon.
Police are still searching for Juvenal Cardenas Mejia, another suspect involved in the crime.
The Associated Press and City News Service contributed to this report.