The Airway Heights Corrections inmate accused of murdering his cellmate appeared in front of a Spokane County Superior Court judge on Tuesday morning, where he pleaded not guilty to First Degree Murder.

Shane Goldsby told KHQ's Kevin Kim that he beat Robert Munger to death, but only after Munger taunted him with the details of raping Goldsby's little sister.

Robert Munger was sentenced to decades behind bars for child rape. One of his victims, Goldsby told KHQ and sources confirmed, was Goldsby's little sister.

Goldsby says he was placed in a cell with Munger sometime in the Spring. He says when he saw who his cellmate was, he asked Corrections Officers to change his cell assignment.

It's unclear if Goldsby ever made a formal request, but it does not appear that Goldsby was granted a cell change.

Goldsby said he was driven over the edge after Munger started telling him details of raping Goldsby's little sister, and eventually lost control. According to court details, he beat Munger to death in a communal area.