BANGOR, Maine (NEWS CENTER)-- The man accused of causing a police standoff during Bangor's fourth of July parade entered a guilty plea Thursday to a federal gun charge. Perrin Oliver pleaded guilty to illegal possession of a firearm by a felon. This was a change from October where he originally entered a not guilty plea.

Given the evidence, Perrin Oliver chose to admit he was a felon in possession of a firearm and ammunition. He, however, has not admitted any guilt in causing the standoff. While in court the 44-year old told the judge he suffers from schizophrenia and has been dealing with it since the early 90s.

Oliver has undergone mental evaluations since the stand off. His attorney claims during the time of the incident Oliver was not on his medications and unable to access anything to control his illness. By pleading guilty the defense hopes it will help to have the court consider the lack of medication.

Defense attorney Jeff Silverstein said, "There was mental health involved and often times that falls outside someone's ability to adequately control. So we are hopeful that the court sentences him in a fair way. Since i've been in contact with him since the beginning of this case he has been incarcerated and has been properly medicated.As a result he does not seem to present within any significant mental health issues of an acute nature."

As a result of the stand-off Bangor's fourth of July parade was diverted. It resulted in an antique fire truck colliding with a tractor and the driver of that tractor Wallace Fenlason, 63, was killed.

The judge will review Oliver's family history, medical records, and criminal past before deciding on a sentence. He faces up to 10 years in prison and a fine of $250,000.