Mark the doctor

Mark opens the door to the police office, someone had called him because a criminal was shot and injured. Where is he? An officer shows the waiting room where they were keeping it saying, "You better prepare to die. We found this beast on the road and it doesn't look like it's from this planet." Mark raised an eyebrow. I thought you said it was a person. The officer chuckles, "Do you want to be paid or not?" Mark sighs, I guess I will have to. He walked into the room and locked the door.