Swept Under (2015)

Meet Morgan. At first glance, she's just your average cleaning lady. She has no problem getting her hands dirty, which is a good thing considering it's not fancy houses she cleans for a living - it's gruesome crime scenes. It's at one of these scenes that Morgan discovers a key piece of evidence overlooked by the forensics team. This, and her knack for reading blood splatter, catch Nick's attention, a newbie detective working the case. The pair soon become unofficial partners on what's become a stream of related murders and the closer they get to solving the mystery the closer they get to each other. But while they succeed in getting a confession from their primary suspect, their feelings for each other risk blinding them to the truth and they find themselves dangerously close to the real killer.

Source: TMDb