The Orchard Park man who admitted to killing his father last summer received the minimum sentence Tuesday in Erie County Court. Time Warner Cable News Reporter Kaitlyn Lionti was in the courtroom as Sean Keenan spoke about the incident and tells us why his attorney hopes the case will help others. 

BUFFALO, N.Y. -- Before learning his fate for killing his father, Sean Keenan told the court Tuesday he was ready for whatever sentence the judge decided. 

"I want to say I'm sorry to my family, and my mom and my dad,"he said."This is something I think about every day and every night, and it's going to follow me for the rest of my life." 

Keenan accepted a plea deal for manslaughter in April. The Erie County District Attorney's office said he beat and stabbed his father, John Keenan, in their Orchard Park home last July. 

"We're here because how very, very sadly, Sean was not able to deal with, and it was not identified, the onset of this bipolar disorder and the mania that was involved," said Kevin Spitler, Sean's defense attorney. "Sean is a decent young man who unfortunately was not properly diagnosed with the mental illness that was affecting him."

Spitler said this crime was so out of character for Sean, and pointed out the crowd of supporters in court to the judge.

"You read all the letters from all the friends, what a fine young man he was. He was a happy kid. He was a good kid," he said.

"It appears based on the information that was provided to me by the psychiatrists and the people who've known Sean for most of his life, that this is a failure of a mental health treatment community," said Erie County Court Judge Michael Pietruszka.

The judge said Sean has no prior criminal history, and the letters sent by his family and friends asked for Sean to receive help rather than punishment. Pietruszka sentenced Sean to 15 years in prison, the lowest amount possible, along with five years post-release supervision. 

"We're hopeful that maybe this will like take off the shroud of mental illness and young people that are suffering will reach out, and it won't be a stigma," said Spitler. 

Sean will be able to participate in mental health programs in prison and gave an update on his progress in court.

"I feel more clear-headed now. I can think differently than I did before, and I take medicine every day," he said.

As for Sean's mother and brother, Spitler said, "His brother is just the rock, and his mom, God bless her, she has had so much to deal with, but I think she's doing pretty well."