Two teenagers charged with killing a Jefferson Township man early Monday during an escape from George Junior Republic may have planned the attack days before.

"Tonight is the night," Jeremy Melvin, 16, allegedly told his roommate hours before police say he and Anthony Machicote, 17, attacked Wayne Lamont Urey Jr., a 43-year-old night supervisor at the Pine Township residential treatment center, stole his truck and drove away.

Melvin, of McKeesport, and Machicote, of Pittsburgh, were charged as adults Monday afternoon with homicide, robbery, theft, aggravated assault and conspiracy after the pair turned themselves in to a security guard at South High School in Pittsburgh. They had Urey's green pickup truck with them, police said.

According to state police, the teens attacked Urey, of Jefferson Estates, just after midnight Sunday in cottage S on George Junior's campus.

At 12:10 a.m., police said a 15-year-old boy on his way to the bathroom was almost knocked down by Machiote and Melvin as they ran past him.

The 15-year-old found Urey in a bedroom, bound with bed sheets and lying on the floor between two beds with a sheet over his face, police said. His hands were tied behind his back and a belt was wrapped around his ankles, they said. Another resident of the cottage got a relief supervisor, who pulled the sheet off Urey's face, saw he was hurt and unconscious and called for help, police said. Despite attempts by staff members and EMT workers to revive Urey, he never regained consciousness, police said.

Urey, who police said had "visible trauma" to his head and a broken leg, was taken to United Community Hospital and pronounced dead at 1:15 a.m. Mercer County Deputy Coroner Scott Black listed Urey's cause of death as suffocation and strangulation; an autopsy was performed by Erie County pathologist Dr. Eric Vey, police said.

Other residents of the cottage told police that Melvin and Machicote tried to get other residents involved in the attack as early as two days ago. They discussed how they would attack the "night man" and asked a 16-year-old to create a diversion so they could knock Urey out, tie him up and steal his keys, police said.

Earlier Sunday evening, Melvin allegedly told his 14-year-old roommate "tonight is the night" as he shadowboxed around their room, police said.

George Junior Chief Executive Officer Rick Losasso said Urey, a 12-year employee of the school, was scheduled to watch the cottage's 11 residents from 10 p.m. to 6 a.m., while a relief supervisor, who was covering for the couple that usually stays at the cottage, was sleeping.

Losasso said that setup was routine.

He said every employee who has contact with residents has a portable "panic button" to alert others to trouble. Losasso said they never heard an alert from Urey's button and didn't know why. He said some students are aware of the panic buttons.

Machiote and Melvin were arraigned by video by District Justice Henry Russo Monday night from the Mercer County Jail, where they are being held without bail pending a hearing Nov. 19 before District Justice Lawrence Silvis, Worth Township.

Losasso would not specify why the two were at George Junior, except to say they were sent there from Allegheny County Juvenile Court.

The Pittsburgh Post-Gazette reported on its Web site that Machicote was sent to George Junior after being found delinquent -- the juvenile court equivalent of guilty -- of unauthorized use of a motor vehicle. Melvin was there after being found delinquent on a charge of assault, according to the newspaper, which didn't identify a source for the information.

The Associated Press contributed to this report.

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