Garner pleaded guilty to raping a 16 year old girl between December 2008 and January 2009.
The girl ended up becoming pregnant as a result.
Garner also admitted to a home invasion in Clarence, where money and jewelry were stolen from the owner at gunpoint in July 2011.
Garner was recently convicted of strangulation in connection with an attack on a woman in June 2011.
Garner is suspected of killing Amanda Wienckowski, whose body was found in a dumpster.
The Erie County medical examiner's office ruled she died of a drug overdose, while other autopsies say she was strangled.