It is a custom coded plugin created by drtshock called "DeadLife" which has over 500 lines of code to make sure there are no bugs. You can find out about DeadLife on his youtube channel by simply searching "drtshock" at www.youtube.com.
Dreadiscool wrote the original DeadLife server, but it was very buggy. Drtshock went through and cleaned it up and fixed some of the bugs.
Dreadiscool coded most of deadlife I believe.... drtshock joined October/November I think, correct me if I'm wrong.