BUFFALO, N.Y. -- Sean Keenan, 22, reached a plea deal with the state Monday, pleading guilty to 1st degree manslaughter in the death of his father, John.

In Erie County Court, Keenan admitted to beating and stabbing his father to death in their Hillsboro Drive home last July.

Keenan's attorney, Kevin Spitler, said he was suffering from serious mental health issues at the time.

"I think this started in May of 2014, and in May, June, up to July, he was really unstable mentally," Spitler said.

Spitler says Keenan shaving part of his head and trying to flee to Canada after killing his father showed that he was not in the right state of mind.

"You know, the manner in which he went, the manner in which he presented himself at the border and stuff, I think was indicative of his very confused and inappropriate mental state," Spitler said.

Keenan said in court that he is taking medication called Abilify which is used to treat bipolar disorder, depression and schizophrenia. Spitler says Keenan's condition has stabilized over the last few months and that he fully comprehends what he is doing in taking this plea deal.

"When appropriate treatment is received by the individual, they are able to revert back to prior to the onset, and so therefore I've been able to converse with my client on a regular basis. He seems to, in my opinion, as I said to the judge, clearly understand everything that was going on," Spitler said.

By taking the plea deal, Keenan avoids not just the murder charge, but also 2nd degree assault and 1st degree attempted escape charges which occurred while he was in the custody of police in Orchard Park.

Ultimately, Spitler and the Erie County District Attorney’s Office stated that after speaking with the family and going over the case, they feel the manslaughter charge is appropriate.

"It's unusual that the family that you're speaking with is the family member of the defendant as well as the victim. Obviously, we take into consideration their feelings as well as the history here and how the family wants to put this behind them." said Erie County District Attorney's Office Homicide Bureau Chief James Bargnesi.

Keenan faces 15-25 years in prison in addition to five years of supervised release. He'll be sentenced on May 20.