Maria and John Granat were found stabbed and beaten last month inside their Palos Township home.
The couple's son is already facing charges. Now, prosecutors accuse three of his friends of helping to carry out what they call a pre-arranged plan to murder.
Christopher Wyma, 17, Mohammad Salahat, 17, and 19-year-old Ehab Qasem all face two counts of first-degree murder, along with the victims' 17-year-old son John Granat Jr.
The three teens were denied bond Tuesday morning.
The three new suspects are all classmates or former classmates of Granat at Stagg High School. All four are accused of beating and stabbing Granat's parents in unincorporated Palos Township on September 10.
The Cook County Sheriff's office said it has videotaped confessions from the three teens saying that they helped killed Granat's parents.
"They knew the parents kept money in their house. So the four of these individuals conspired over the course of a month to kill John Granat's parents and take the money," said Cook County Sheriff Tom Dart.
Dart says Salahat stayed in the car while Wyma and Qasem met Granat inside to carry out their plan. Prosecutors say they used the code "the concert was on."
"The other ones went inside the house where they grabbed baseball bats and a knife. They went up to the bedroom where John and Maria Granat were sleeping and there they viciously murdered the couple," Dart said.
Granat Jr. called 911 to report the murders the next morning, saying that he was sleeping the entire time, but investigators said that his story did not add up.
Dart said the motive for the murder was money. John Granat was in the construction business and kept more than $35,000 in cash at home. Dart says after the murder Granat's son divided up the cash and gave it to the other suspects.
While Stagg students are shocked about the charges, lawyers for two of the suspects were quick to defend their teenage clients.
"I hope everybody will just wait and see what the physical evidence, what the real forensics show and not what some child said after being locked with very big policemen with guns after being deprived of his statutory rights," said Joel Brodsky, Mohammad Salahat's attorney.
"He does take antidepressants and anti-anxiety medication and we'll have to see if that played a role in the interrogation he was subjected to. It will be a long road," said John Russell, Wyman's Attorney.
A neighbor of Salahat does not believe the 17-year-old was involved.
"They are a good family and Mohammad is a good kid," said Lena Muffareh.
Stagg senior Angelo Angelos says during the past couple weeks Wyman talked about the murder at school, blaming it all in his friend, John Granat.
"It was weird that he would talk about it when he was actually one of the ones who helped. Because he just said, 'John did it, John did it,' and wejust thought it was weird he would sell his friend out like that," said Angelos.
Stagg officials said they are providing counselors for the students.
Granat, coincidentally, also had a status hearing scheduled for Tuesday morning.