"He was way more than a friend," Echevarria said. "He was my brother."
And so, three weeks later, he still can't believe that he killed his best friend on Jan. 21.
Hopkins' mother, Bernadette Lamberto, has forgiven Echevarria. "There's no doubt in my mind that this was an accident," Lamberto said. "I forgive Hec, and I know Billy would, too. I told him he has to forgive himself in order to move on."
The teen, however, struggles to cope with the memory of that afternoon.
"I don't forgive myself for what happened at all," a tearful Echevarria said last night as he sat alongside Lamberto in her home on Hellerman Street near Loretto Avenue in Oxford Circle. "It was just an accident. I would never do that to Bill."
Charged with murder
According to police, Hopkins, 19, was shot once in the chest in the Echevarria family's home on Mascher Street. He was pronounced dead at the scene shortly after officers arrived.
Echevarria was arrested the next day and charged with murder, involuntary manslaughter and related offenses, according to court records.
He's out now, after posting $10,000 bail, awaiting a preliminary hearing scheduled for tomorrow morning.
Lamberto said that her initial reactions to the news of her son's death were the same as any mother's would be: anger, grief, fear.
But when she was told of the circumstances, she calmed.
"If it was anyone else besides Hec, this would be a totally different situation," she said.
"Am I mad? Yes, of course.
"Billy's life is lost, but Hec's life is lost, also."
To hear Echevarria tell it, the shooting was a terrible, tragic mishap:
The teens were hanging out at the house on Mascher Street, working to repair Echevarria's ATV ahead of the coming snowstorm.
Echevarria's older brother was staying at the house preparing to move into a new apartment. He had brought along his possessions, including a pump-action shotgun.
The younger Echevarria felt comfortable around the gun. He had shot it before at the range with his brother, and never played with it or handled it alone, he said.
And when Hopkins asked to see the gun, the brothers obliged.
"I unloaded it, watched all the shells drop onto my bed," Hector Echevarria said. "I went to pass it to [Hopkins,] and it just went off."
'It didn't seem real'
Time stood still after that, Echevarria said.
"I didn't know what to do; I didn't believe it," he said. "It didn't seem real."
In the days since the shooting, Echevarria said, he's still reeling, unable to process everything that happened.
"I never had to deal with court before, and now I have to deal with it for my friend?" he asked somberly, fighting back tears.
"Out of everything it could have been, it's for my best f---ing friend."
Lamberto said her family and friends forgive Echevarria and will act as a support system for the teen, whatever punishment he may receive.
"We'll be there; we'll write and we'll visit," she said. "And when he gets out, I hope he'll live his life the way Billy would want him to."
In the meantime, everyone who knew Hopkins is sharing memories. Photo collages line Lamberto's living room, showing her son goofing around with friends, posing in his baseball uniform and dressed up as Santa Claus for a recent Christmas party.
A life-size photo of Hopkins leans in the corner of the room, a gift from a family friend for the teen's well-attended viewing.
"There were 450 people there; it was packed," Lamberto said. "Billy would always say, 'When I leave, make sure it's a party,' and he got what he wanted."
Lamberto is grateful for the support, and is confident that with the help of her friends and family, she'll push through her grief.
"I don't think it's hit me yet," she said. "I feel like I'll get a call saying, 'Hey, Mom, open the door.'
"We'll get through this; it's what Billy would've wanted."
On Twitter: @Vellastrations