Deathloop: Who is the Killer?

Lucas found himself stuck in a never-ending time loop on his birthday. In the bathroom stall, he was killed by a guy in a clown mask. At first, when he woke up on his couch, he thought it was just a dream. But when he ended up in the bathroom for the second time, he felt a nagging sense of alertness. Yet, the killer still struck. After the third time he was reborn, he finally understood what was happening. He realized he needed to escape the killer to break free from the time loop. Just as he was about to get in the car with Josie, a truck came out of nowhere and ran them over. After waking up for the fourth time, he decided it was time to investigate everybody one by one. And just when Josie was having a scuffle with David, a clown mask fell out of David's bag...