Warning: Spoilers for Dead to Me season 2 are ahead.
Of all the people that Dead to Me's Judy (Linda Cardellini) could have picked to date after leaving her disastrous relationship with Steve (James Marsden), she had to pick a cop. To be fair, Judy didn't know that Nick (Brandon Scott) was a cop when she first met him at a grief retreat. But once she knew, she probably should have said goodbye, because Nick soon learned that Judy killed her friend Jen's (Christina Applegate) husband Ted in a hit-and-run.
After meeting Nick in season 1 at the grief retreat, Judy introduced Nick to Jen, who immediately wanted his help solving her husband's hit-and-run. Nick had experience with that type of crime, and Jen was desperate for answers. It wasn't long before Nick got close to the truth. His sleuthing with Jen (and Judy who tagged along to cast suspicion elsewhere) revealed the make and model of the car that hit Ted. And soon Nick learned that Judy and her ex, Steve, owned the very same car. He put two and two together to realise that Steve and Judy broke up shortly after the hit-and-run and that Judy quickly forged a friendship with Ted's wife Jen. He believed Judy and Steve were responsible for Ted's death. Nick brought his suspicions to Detective Perez (Diana Maria Riva), but she blew him off, reminding him that since he'd dated Judy, it could make his motive for looking into her suspicious.
However, even when Perez began putting together clues of her own that pointed to Steve and Judy as the hit-and-run culprits, and even when Jen came to the police with news that Judy had confessed to her, none of it was enough evidence to actually process either Judy or Steve for the crime.
Warning: This is where Dead To Me season 2 spoilers begin.
In season 2, the police turned their attention to Steve's disappearance over the impossible-to-prove hit-and-run. The chief of police tried to pin the disappearance on Judy, since she'd turned Steve in for money laundering and drained his bank account, but Nick wasn't so sure. Even though he believed Judy to be capable of a hit-and-run, his investigative skills pointed him to the fact that something bigger was afoot with Steve. So Nick told the chief that he thought the Greek Mafia members that Steve worked for might be better suspects, only to be told to stay on the Judy theory.
There was incentive for the chief to keep eyes off the Greek Mafia, because it was later revealed that the chief was working with Steve and the mafia. Thankfully, Nick didn't drop his own investigation when the chief told him to focus on Judy. He later gave a folder to Perez that seemed to point to the mob members. The folder contained photos of a mob member going into Steve's art gallery, but Perez dismissed it saying it wasn't enough to build a case on. Nick, my man, you've gotta start collecting more evidence to back up your claims!
Lucky for Nick, Judy was able to clear her name and do Nick's job for him in the final episode of season 2 when she gave him a bag containing Steve's burner phone, flash drive, and recordings that implicated the Greek Mafia as well as the police chief in illegal activity. Nick seemed pretty surprised by the chief's involvement in things (again, how, Nick?), but glad to take him down for his crimes. Nick's folder pinpointed the mafia alone, until the chief's role in things fell into his lap. In the end, the chief and some of the mafia members went to prison, thanks to Nick and Detective Perez — and the presence of, you know, actual evidence.