Solve the murder case (idea/storyline)

You have been given a case to solve. Even though your partner is on the case, they need your help to solve it. The office gives you a paper which is the report of the case, on the report there is a marker for you to scan. Scan the marker that is on the paper, a video of your partner will appear. He will brief you on the case and what they have covered so far. A girl was murdered in Taylor's Lakeside campus. They found a wound on the body, it was a knife wound, the victim was stabbed multiple times but they couldn't find the knife. This is where you come in and help, search the area for the knife and it will lead you to another clue. Once you've found the knife, there will be a marker on the knife which you have to scan. After you scan it, a video in first person view of the murderer stabbing the victim, but the place that she was stabbed wasn't where the body was found. Watch the video carefully and know where exactly she was murdered. Go to that area and before you enter the room there will be scanner for you to scan, scan it and a video of the victim being tied to a chair and her mouth covered with a cloth and the voice of the murderer talking to her and the video will end. To know what happen after, you have to enter the room and find any clues that you can find. In the room there will be 2 object, one is the cloth that was used to cover the victim's mouth and the other one is the rope that was used to tie her on the chair. Those 2 objects are scannable, but you can only scan one of them because if you scan the cloth the rope will be unscannable and vice versa. Now, if you scan the cloth it will lead you to the suspect and immediately you have to find him and catch him. After you catch him, you realize that on his shirt there is a marker, scan it and a video will be played, the video will say "The real suspect is still out there" You only caught the one who helped the primary suspect, basically it's a game over. If you scan the rope however, the video will show you a mysterious man with a familiar voice talking to the victim then the video will be cut and continued right after the man killed the victim, you will hear him laughing and as he grabs the camera his face was shown. It's a very familiar face, it's your very own partner who is the murderer, he was the real killer.