Exactly what caused the death of a North Forsyth High School student earlier this week remains undetermined, authorities said.

The body of 15-year-old Trey Scott Spencer was sent Monday to the Georgia Bureau of Investigation’s Crime Lab in Atlanta for an autopsy.

Forsyth County Sheriff’s Capt. Tim House said it could take anywhere from days to weeks before the results are released.

Spencer was discovered lying unconscious Monday morning in the back yard of a home at 9035 Walnut Cove Court.

He was found by a 14-year-old friend who lived there and with whom he reportedly had been drinking alcohol and taking drugs the night before.

Spencer was taken to Northside Hospital-Forsyth, where he was later pronounced dead.

His death has had a profound impact on students at North.

Jennifer Caracciolo, spokeswoman for Forsyth County Schools, said counselors have gone to classrooms to work with students and will continue monitoring the situation throughout the week.

"The students organized a prayer at the pole [Tuesday] morning, as well as a Fellowship of Christian Athletes prayer at the pole [Wednesday]," Caracciolo said.

She said students dressed in camouflage for Tuesday’s vigil.

According to other reports, students also gathered Tuesday night at Browns Bridge Community Church on Browns Bridge Road.

Describing Spencer’s death as a "tragedy," Sheriff’s Maj. Dan Jagoe cautioned that drug and alcohol abuse has consequences.

"If there’s anything I want to get across to young people today, it’s please don’t do this," Jagoe said. "If you think you have to do this, contact your parents, contact your [school] counselor, contact a friend of yours.

"You don’t have to do this to have fun."

Jagoe said he did not know if Spencer’s parents expected him home Sunday night.

The family has declined to publicly comment on the matter.

According to a sheriff’s report, Spencer’s friend told authorities the boys had been hanging out Sunday night at the home on Lake Lanier.

In the report, he said they had been drinking bourbon, smoking marijuana, huffing dust cleaner and taking Klonopin, a prescription medication used to treat anxiety and seizures.

The younger teen said his 18-year-old sister told him to come inside at about 10:30 p.m., at which time he thought Spencer had walked home.

The 15-year-old lived less than a mile away on Fairlane Trail.

Robert and Laura Lancaster, the parents of the siblings, returned to the family’s house about 6 a.m. Monday from a trip to St. Simons Island.

After spotting Spencer in the yard, the 14-year-old told his father and they called 911, according to the report.

While executing a search warrant on the Lancasters’ home as part of the death investigation, authorities found what they have described as "deplorable conditions."

Jagoe said a decaying opossum carcass was lying in the foyer. Throughout the house, authorities found animal feces, live and dead rodents and food that had been left out.

Robert Lancaster, 46, and Laura Lancaster, 52, were arrested Monday and charged with second-degree cruelty to children.

They were released Wednesday afternoon from  the Forsyth County Detention Center after each posted bond of $27,500, House said.

Jagoe said the couple was arrested "for the condition of the house and for the children being in those conditions."