Casey Marleen Downey, 20, was found dead inside this home in North Preston on Sunday. (CBC)

RCMP are treating the death of Casey Marleen Downey in North Preston, N.S., as a homicide.

Downey, 20, was found dead Sunday in a home in the community east of Halifax. RCMP officers discovered his body just before 6:30 a.m. while responding to two 911 calls about weapons.

There was a party underway in the house at the time, RCMP said, but they haven't been able to interview everyone who was at the party.

The RCMP has not said how Downey died or whether a weapon may be involved. Investigators believe this is an isolated incident.

RCMP spokeswoman Const. Tamu Bracken said the young man was visiting 1166 Downey Rd. and there were other people inside when officers arrived.

Sharon Downey, Casey's cousin, described him Monday as being quiet and mannerly.

"It's my relative, and it's really sad," she said. "He was so quiet, he was nice — a lot of manners and stuff like that. I was just talking to him the other day and we talked and hugged and stuff like that. I didn't see anything else."

The slaying happened across the street from 81-year-old Winnifred Willis Beals's home.

She remembers Downey as a helpful teenager.

"I know Casey well. He picked blueberries for me and he went and helped me to sell them," Beals said.

Downey was trying to finish his high school education, his cousin said. She doesn't understand how he met a violent death.

"It's just rattling in my brain, I don't make no sense of it at all. I don't know what's going on," she said.