UPDATED 09/13/11 4:47 p.m.
PALOS PARK, Ill. (CBS) -- Bond has been denied for a 17-year-old high school student, who is charged with beating his parents to death in their home in unincorporated Palos Park.
As CBS 2's Susanna Song reports, a judge denied bond for John Granat Tuesday morning at the Bridgeview Courthouse.
He's accused a murdering his mother and father sometime between 10 p.m. Saturday and 3 or 4 a.m. Sunday inside their home. Investigators believe he used a weapon to brutally beat them and another to stab them.
LISTEN: WBBM Newsradio's Bernie Tafoya reports
His father, also named John Granat, 44, and mother, Maria Granat, 42, were found dead Sunday in their home in the 12700 block of 81st Court in unincorporated Palos Township.
Autopsies on Monday found John Granat died from multiple blunt force injuries from an assault, while Maria Granat died from multiple blunt and sharp-force injuries. Both were ruled homicides, the medical examiner's office said.
Both of the boy's parents suffered blunt force trauma to the head, while Maria Granat was also repeatedly stabbed.
As CBS 2's Mai Martinez reports, Cook County Sheriff Tom Dart said that, after possibly trying to clean up the crime scene with bleach or ammonia, Granat called 911 around 7 a.m. Sunday.
Granat told police that he had fallen asleep in the basement of the home around 12:30 a.m. Sunday, and was home the entire night. He claimed he woke up to find the house ransacked, and his parents dead.
But police say this story was proven to be untrue. It turned out that he had been pulled over by Palos Heights police for a minor traffic offense at 122nd Street and Harlem Avenue at 5:17 a.m. that morning, sheriff's police said.
Sheriff's police said several conflicting stories came out of Granat's mouth, until finally, he told investigators that he had needed money, and let a friend come into the house while he was out. Granat said he fell asleep in his own car and didn't come in until 7 a.m., when he found his parents dead, according to sheriff's police.
But sheriff's police concluded that Granat himself was the killer, and found out from several friends that he had threatened to kill his parents several times before.
Dart said there were "absolutely no signs of forced entry" at the home.
As for a motive, Dart said, "It's clear that the defendant had a difficult relationship with this parents at times and at different times he made threats. … He made threats to kill them."
But Granat's attorney said police have the wrong man.
"There's no way that that young man could have done that those two human beings," defense attorney Rick Beuke said.
Some of his classmates at Stagg High School also said they find it hard to believe.
"He was a pretty nice kid and I never would've expected that and I feel bad for him," said senior Nikki Graczyk.
Neighbors said the family had lived in the home for a while, and that John Granat was a local contractor and owned a family home improvement and landscaping business in the area.
Granat is to return to court for a preliminary hearing in one week, on Tuesday, Sept. 20.
for more features.