Joe Cruz (Joe Minoso) messed up. The character really stepped in a world of trouble when he agreed to help a former gang member commit a robbery. He wound up shot, and was forced to sit by and act like it wasn't bothered while his friend, Kelly Severide (Taylor Severide) conducted an investigation.
It was never going to end well for Cruz, so he came clean. In the episode "Chaos Theory," the veteran firefighter approached Severide and admitted to the incident that led to him shot. He admitted he let a man named Flaco (Jose Antonio Garcia) die during a building fire in season 1, because the man had threatened his brother. This piece of blackmail was why he agreed to help with the robbery.
Joe Cruz was suspended from duty for two weeks
The firefighter was expecting the worst. He even confessed to Chicago PD veteran Kevin Atwater (LaRoyce Hawkins), fully expecting to be placed under arrest. He was not arrested. Cruz was indeed forced to step back from his position at Firehouse 51, which is why fans have scrambled to make sense of what comes next, but he will not be gone for good.
Cruz was suspended for two weeks without pay. Chief Dom Pascal (Dermot Mulroney) determined that the character's behavior was unbecoming. "Setting aside everything else," Pascal explained. "You withheld information from the firehouse, and you lied to me. That's unacceptable."
It's hard to argue with Pascal's ruling. He did, however, cut the firefighter some slack for coming forward and confessing on his own accord. He asked Cruz why. Even after Severide told him he was in the clear. Cruz's answer was simple, and tied in with a tender conversation he had with his son Javi in an earlier scene. "I wanna be the man my son thinks I am," he asserted.
Cruz will return for the One Chicago crossover
Chief Pascal was pleased. "I'd say that's a worthy goal," he responded. "I'll see you in two weeks." So yes, Cruz is technically leaving Chicago Fire, but the character will only be gone for a bit before he's back up and running.
Joe Minoso has spoken at length about his excitement for the One Chicago crossover, which is set to air Wednesday, January 29. This lead us to believe that the character is either called for emergency, given the severity of the situation, but Chicago Fire showrunner Andrea Newman confirmed that the character will be MIA as a result of his suspension! Pennance for his mistakes! The good news is that Cruz will be back soon.