Melvin Vernell III was shot and killed in June 2012 outside a hospital where he was awaiting the birth of his child.
On Friday, prosecutors said the gunman, 25-year-old Deandre Washington, was convicted of murder and other charges and sentenced to life without parole plus 20 years.
Also convicted were 35-year-old Gary Bradford and 29-year-old Maurice Conner on charges of conspiracy and participating in criminal street gang activity. Bradford was sentenced to 25 years in prison, and Connor, 30 years.
Prosecutors say the three men conspired to kill Vernell in retaliation for a drug robbery they believed he had orchestrated. A fourth defendant awaits trial.