A high school student broke into a Lancaster home last month to kill a classmate and went on to slay both the teenager and his parents, police charged Saturday.

Alec Devon Kreider, 16, of Lancaster, was arrested after his father told police that he had confessed to the killings, Manheim Township Police Chief Neil J. Harkins said at a news conference.

Kreider and the teenage victim were friends and fellow high school sophomores, officials said. Authorities described Kevin Haines, 16, as the intended target, but declined comment on a possible motive.

"This was not a random act," said Lancaster County District Attorney Donald Totaro, who added that authorities believe Kreider acted alone. "He broke in with the intent to kill."

Thomas Alan Haines, 50, Lisa Ann Haines, 47, and their son were found stabbed to death on May 12 at their house in a leafy neighborhood in Manheim Township. Their college-age daughter ran to get help and survived.

Click here for photos of Thomas, Lisa and Kevin.

Margaret "Maggie" Haines told police she was awakened by a noise at about 2 a.m. and went into her parents' bedroom, where she said she found her father lying on the bed and her mother sitting nearby. The mother quietly told her to get help.

When police arrived a short time later, they found the parents dead in their bedroom and the son in a hallway.

Kreider went to the home intending to smother Kevin, but instead stabbed him in the neck and chest, according to a police affidavit. Thomas Haines was stabbed in the chest and his wife in the abdomen.

Kreider, who attends Manheim Township High School, was charged as an adult with three counts of murder. He was being held without bail following an arraignment Saturday.

Defense lawyer John A. Kenneff said he has asked to postpone a preliminary hearing scheduled for Wednesday, but otherwise declined comment.

Kreider allegedly confessed Tuesday to his father, Timothy Kreider, who went to police Thursday evening. Police spent the next two days investigating before making an arrest.

Police had previously interviewed the suspect, who continued to go to school until it let out for the summer.

"He was certainly someone who had been looked at and interviewed by police," Totaro said.

The Kreider family does not plan to comment, their lawyer said.

"The Haines family remains and will continue to remain in the forefront of their thoughts and in their prayers," said lawyer Robert Byer, who attended the news conference.

Police previously said that they found the family's back door open, and nothing taken from the house. Kreider was also charged with burglary.

Kevin Haines was a sophomore at Manheim Township, where he was a member of the German club and Quiz Bowl team.

Maggie Haines, a 2005 graduate of Manheim Township, had returned home just days earlier after finishing her sophomore year at Bucknell University.

Thomas Haines was a salesman at Motion Industries in Lancaster, while his wife taught at Lancaster Brethren Preschool.

Several people coming and going at the Kreider home, about two miles from the crime scene, declined comment Saturday.

A police forensics unit visited the home Friday night, neighbor Alan Isacson said. He did not know the family, but said he was relieved by the break in the case, which had led police to advise residents to lock their doors.

"Any time a murder is solved, it's good news," the 37-year-old Isacson said.

Click here for photos of Thomas, Lisa and Kevin.