Hank Voight (Jason Beghe) and Erin Lindsay (Sophia Bush) have always displayed a strong sense of friendship, often to the point where they seem like father and daughter watching out for each other. However, Cartermatt reports that the two won't be seeing each other eye to eye in "Chicago PD" season 4 and their friendship will be tested.

Back in season 3, Voight's son Justin (Josh Segarra) was killed and the elder detective decided to outright kill the culprit responsible. He did tell Lindsay to stay away so she wouldn't witness him commit the act and to ensure she wouldn't be implicated in the crime. He not only killed the enemy but went ahead and buried them as well.

However, it is pointed out in the report that Lindsay did see him committing the deed and the images of his crime are going to haunt her in season 4. According to a report from Ecumenical News, this could even mean she can be investigated for not reporting the incident or Voight's involvement. She may even be charged as an accessory to murder.

In an interview with TV Guide, this is going to cause an issue not just between Voight and Lindsay but also with Halstead (Jesse Lee Soffer).

"Voight's a father figure to her. So she's going to try to take care of him," explained Soffer. "What's really important for Halstead is making sure that Lindsay doesn't end up in jail, Lindsay doesn't end up going down with Voight. She lost her brother, essentially. This season more than any other, Lindsay and Halstead are going to really rely on each other."

The report also reveals that the studios are planning on introducing Lindsay's real father into the show soon although there are no guarantees yet and no actor has yet been cast for the role.

"Chicago PD" season 4 premieres this Sept. 21.