|Season unknown, Episode unknown|
|Air date||April 2, 2017|
|Written by||Elizabeth Rinehart|
|Directed by||Donald Petrie|
Double Helix is the seventh episode of the first season and the 7th overall episode of Chicago Justice.
Nagel and Dawson are disturbed when they investigate the brutal murder of a pregnant woman whose unborn baby was cut from her stomach. Stone and Valdez begin to prosecute the person involved. Soon after, the evidence points to the killer being related to a serial killer that Stone put away. Meanwhile, Nagel files a petition for joint custody of her daughter.