Chained but unbowed and apparently unfazed, Aaron Congdon pleaded guilty to killing his father Tuesday.

Congdon of Chittenden faced a charge of first-degree murder in the shooting death of his father, Bernard Congdon Jr., but accepted a plea deal that lowered the charge to second-degree murder.

Under the terms of the plea deal, prosecutors agreed to ask for a sentence of 22 years to life in prison while the defense will be allowed to argue for any applicable sentence under the charge, which carries a minimum sentence of 20 years in jail.

The plea deal came as a surprise development during a morning hearing at Rutland District Court. The court was scheduled to hear arguments about whether the case against Congdon, who turned 17 in August, should be transferred to juvenile court.

Congdon, who wore a blue shirt, black pants and sported the beginnings of a Mohawk, calmly agreed to the deal, which would send him to prison at least until his mid-to late 30s.

The only emotion displayed in the courtroom, which was mostly empty save for lawyers and experts slated to testify in the case, came from a former girlfriend of Bernard Congdon Jr., who sobbed as the plea deal was sealed.

Judge William Cohen accepted Congdon's plea and said he will set aside a full day within the next two months for sentencing arguments.

Rutland County State's Attorney James Mongeon said during the hearing that prosecutors decided to lower the charge against Congdon in part because of his mental state at the time of the killing, which Mongeon said would probably lead to a verdict of second-degree murder.

Congdon's court-appointed attorney, Matthew Harnett, has argued in the past that Congdon suffers from mental illness and was found to be insane at the time of the killing.

However, when questioned by police days after the murder, Congdon said the killing wasn't spontaneous.

"Congdon replied if you are asking if this is premeditated, then the answer is yes," police wrote in an affidavit. "Congdon then stated he has thought about killing his father for some time."

Congdon shot his father on May 3, 2007, inside the home they shared on Powerhouse Road in Chittenden. He was arrested two days later at a friend's house in Rutland.

After his arrest days later, Congdon admitted shooting his father in the face with a .30-30 rifle while they were standing in the kitchen and to shooting the two family dogs with a .357 revolver, according to court records.

Congdon told police he was talking on the phone with his friend Edward Walker when he paused and put down the phone. With the connection still open, Walker overheard "two large bangs" and "what sounded like glass breaking."

"I did it," Congdon said when he returned to the phone, according to court records.

Congdon didn't tell police why he killed his father, but according to documents Harnett filed with the court, Congdon's relationship with his father, who served as a selectman in Chittenden, had been deteriorating for some time prior to the shooting.

According to Harnett, Congdon's relationship with his father was strained by incidents including the son wrecking his father's "beloved Corvette" and the father's accusations against his son about taking money.

In addition, Harnett wrote that the death of Congdon's mother, Pamela Hesse, was a "crushing" blow to the adolescent. Congdon was two weeks shy of his 15th birthday when his mother died in a motorcycle crash in August 2005.

Harnett wrote that Congdon suffers from "major depressive disorder, recurrent, severe; and depersonalization disorder," and suffered from those mental illnesses during the shooting.

Congdon had a tumultuous family life, according to court records, with his parents separating when he was 7. During his childhood he endured parental disputes over visitation and custody.

Elementary and middle school records also show that Congdon had been an "emotionally disturbed" child, with his parents' divorce said to have gotten in the way of his education and maturation.

Congdon and his father did try counseling and family mediation, but their relationship continued to worsen, according to court records filed by Harnett.

In the time leading up to the shooting, Harnett's filing stated, the relationship "hit rock bottom" as Congdon was "disenrolled" from Rutland High School, had been involved in a retail theft, and used drugs and alcohol.

A snapshot of Congdon's emotional state just before the shooting can be found on his MySpace account, where the teenager's profile is littered with references to drug use, sex and violence.

In the final posting on the site submitted just days before the killing, Congdon wrote "every (expletive) thing i do leads to nowhere. every question i ask leads to more questions, you leave me at a dead end, why the (expletive) am i like this. i am ... different, so much (expletive) DIFFERENT. THAN EVERYONE !!! me, ed, stu, and tiana are all "alike" more than anyone ive ever met. .... but i still feel different than them. like there is something that even they dont get. WHAT THE (expletive). my (expletive) HEAD !!! WHY THE (expletive) AM I LIKE THIS. what the (expletive) is happiness, (expletive) happiness. (expletive) YOU !!, i (expletive) hate this. id kill all you mother (expletive) and still not be happy, but it would be a good start. i want sombody ... "there" to fill that emptiness when no one else can. (expletive) THIS, im so (expletive) up, y cant some one help me, ...i need you. ANYBODY? (expletive)!!!. OUCH , ,,,, , you didnt reply., tiana it wouldve taken 2 seconds to reply to me. instead you left me with a dead end. it will keep me up tonight. its going to (expletive) with me. you didnt talk to me, (expletive) stuart, WHAT THE (expletive) IS WRONG W/ YOU?"