Alone in the Dark: The New Nightmare

I need help in killing the flying creature in the library. I have shot him several times and he won't die. I can't open the library doors to get out and I assume it's because I haven't killed the creature yet. I have emptied my shotgun and pistol into him but he won't die. I am hitting him most of the time because he reacts by moving and sometimes fly's away but always returns. Any suggestions as what to try?

Thanks to all

Apparently this guy is hard to kill, Lone Wolf. Here is what a walkthrough says about him: To kill him, use your shotgun or pistol. Shoot at him. You will miss but he will curl up in a ball and then unfurl. When he does shoot him. You need to do this about 10 times to finish him off......