A teenager in a Chicago suburb who pleaded guilty to fatally stabbing a 15-year-old was sentenced to three years of probation and to complete community service hours. 

"When the defendant stabbed my son, he stabbed the heart of my family," the victim’s mother, Marcela Fierros, said in a statement that was read in court Monday. 

The unidentified defendant pleaded guilty to second-degree murder after 15-year-old Elias Valdez was fatally stabbed in August of 2020 in Glenview, which is about about 20 miles from Chicago. The defendant was charged as a juvenile in the case. 

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In addition to probation and completing 100 community service hours, a Cook County judge ordered the 17-year-old high school senior and his parents to participate in counseling.

The stabbing unfolded when Valdez tried to buy marijuana from the defendant but tried to take the drugs without paying for them, according to police. The defendant chased Valdez, ending with the two fighting and the defendant stabbing him with a utility tool. He died later that day in the hospital. 

"I’m mad," Valdez’s sister, Elizabeth Valdez, told the Chicago Tribune after his death. "It’s not fair how he passed away. It’s not fair to know that he’s gone and I’m not receiving answers."

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The 15-year-old’s family wanted the defendant to be charged with first-degree murder, and protests were held last year when he was instead charged with second-degree murder and held on home monitoring.

"I feel sad for the loss of my son," Fierros said in Spanish in September 2020. "I also feel angry because justice has not been given."

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The death comes as Chicago struggles with teen flash mobs in the city. Twenty young people were arrested in the city one weekend this month for disorderly conduct, battery and reckless conduct. A city bus driver was also attacked on the street the night of Dec. 4 and required hospitalization. 

Chicago Police Superintendent David Brown responds to a question about the Memorial Day weekend violence during a news conference Tuesday, May 26, 2020, in Chicago. Shootings in Chicago left multiple people dead and at least 39 others wounded in the city's deadliest Memorial Day weekend since 2015. (AP Photo/Charles Rex Arbogast)

Chicago Police Superintendent David Brown responds to a question about the Memorial Day weekend violence during a news conference Tuesday, May 26, 2020, in Chicago. Shootings in Chicago left multiple people dead and at least 39 others wounded in the city's deadliest Memorial Day weekend since 2015. (AP Photo/Charles Rex Arbogast) (AP Photo/Charles Rex Arbogast)

"If you come downtown or anywhere else, let me repeat, or anywhere else to engage in disorderly conduct or crimes, you will be arrested," Chicago Police Superintendent David Brown said last week.

Democratic Mayor Lori Lightfoot said "swift action" would be taken against the perpetrators and called on parents to take responsibility for their kids.

FILE PHOTO: Chicago's Mayor Lori Lightfoot speaks during a science initiative event at the University of Chicago in Chicago, Illinois, U.S. July 23, 2020. REUTERS/Kamil Krzaczynski/File Photo

FILE PHOTO: Chicago's Mayor Lori Lightfoot speaks during a science initiative event at the University of Chicago in Chicago, Illinois, U.S. July 23, 2020. REUTERS/Kamil Krzaczynski/File Photo

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"These kids have to take responsibility, but I’m going to say the parents have to take responsibility," she said. "Do you know where your kid is? Are you making sure that you’re talking to your children about how they should act in a large crowd?"