What law and Order svu Episode is the one where the Killer drains blood from the victims?

Hi I am Trying to figure out what Episode it is where the killer drains the blood to kill his victims. He has it set up where it drains at a certin rate and SVU has only so much time before she dies. Svu then lies to the killer to make him believe that they ran out of time and that she is dead and he tells them where to find her.. Which SVU episode is?? I cant find it anywhere Thanks Soo Much!! :-)