Willy's behavior quickly deteriorated and became more dangerous. "We began finding knives and stuff put in different places," he said.
Bruce laments that his son was the worst he had ever seen him, and he feared for the safety of his wife and two younger sons.
By June 2006, two months after Willy's return from Riverview, Bruce had become so worried that he called home several times a day just to check in on Amy.
One morning, she didn't pick up.
"I called her at 9 o'clock in the morning and there was no answer. ... I called again and there was no answer. I was starting to get very anxious," he said.
With an instinctive feeling that something was wrong, Bruce decide to leave work early and return home.
"I opened the door ... I could see big splotches of blood ... and I opened the bathroom door and I saw two legs sticking out of the bathtub ... and I saw that it was Amy," he said.
Willy had murdered his 47-year-old mother with a hatchet, and later told officials he thought the Pope had ordered him to kill her because she was an al Qaeda operative.
In 2007, Willy was found not guilty by reason of insanity. Today, diagnosed with paranoid schizophrenia, Willy is back at the Riverview Psychiatric Center, but this time indefinitely.
With his father by his side, Willy, now 28, told ABC News what was running through his mind at the time of the crime, and why he rejected treatment. "I didn't believe I was ill," he said. "In fact, I totally took a stand ... completely fought against them about it."
Bruce and his son have agreed to share their story in hopes that something like this never happens again. Bruce blames the poorly treated illness and cracks in the mental health system for the horror he has had to live though. "[Willy] had lost everything when mental illness took over his mind," Bruce said.
Today, at age 28, Willy is remorseful. "I miss everything about her," he said. "I miss getting hugs from her the most, though."
Willy is taking college classes via correspondence while at Riverview, and even hopes to become a lawyer someday -- and says he now takes his medication religiously.
"If somebody's sick, they need to be medicated," Willy said. "There's a chance that they could commit a serious crime. I ended up ... killing my mother and ... I definitely feel the illness should go medicated, not un-medicated."
But, right now, in Northampton, Mass., Caty Simon, 28, is attempting exactly what the Bruce family fears most: She is gradually withdrawing from her psychiatric medication.
In her lifetime, Simon, who works with the a Mad Pride group called The Freedom Center, says she has taken everything from Zyprexa to Prozac to Wellbutrin to Deprico. Now she's attempting to wean herself off one last drug --- benzodiazepines, which are often used to treat anxiety and panic disorders. Simon followed Mad Pride's own instructions on how to safely withdraw from medications, published in booklets such as "The Harm Reduction Guide to Coming Off Psychiatric Drugs."
In a video diary she shared with ABC News, Simon gives her account of what it's like to withdraw from meds so that others could see how it can be done safely and effectively.