Four 19-year-old men have been charged in a shooting that killed a teenage boy and critically injured a teenage girl in north Suburban Skokie last week.

SKOKIE, Ill. (WLS) -- Parents of murdered Skokie 17-year-old Maxwell Gadau speak after funeral, 4 charged in shootingThe parents of a 17-year-old Skokie murder victim are speaking out Sunday night after four young men were charged with their son's killing.Three of the four men charged were in court Sunday and all of them were denied bond. Prosecutors admit that they still do not have the person who pulled the trigger. News of the charges came just hours before Sunday's funeral service for Max Gadau."We told them, 'Smile. Smile and be strong because that's what Max wanted,'" said Patricia Gadau, Max's mother.Patricia and Peter Gadau buried their son Sunday. The 17-year-old Niles North High School varsity swimmer was shot and killed in Skokie last Sunday, in what appears to have been a botched robbery attempt of a friend he was with. And now, the news comes that two of those implicated were his friends, one of them in particular."When they were on the swim team together, this individual was a couple of years older than my son, very much a mentor to Max," Peter Gadau said. "To think that somehow this individual was involved in the murder of my son is devastating."Charged in connection with the murder are Dzevad Avdic, Jeremy Ly, Myles Hughes and Nicholas Smith, all of them 19 years old. Avdic and Hughes are Niles North graduates.In court Sunday prosecutors said it all started when Avdic decided to rob an as-of-yet-unidentified 17-year-old girl he had agreed to buy some pot from. When they met last week Max Gadau was in the car with her, but apparently not involved in the deal. When she refused to simply hand over the drugs, prosecutors say a fifth suspect, who has yet to be arrested, shot Gadau in the back and the 17-year-old girl in the face.Following bond court, the accused's families left without comment, but the attorney for one of them denies his client's involvement."He didn't know the victims at all," defense attorney Edgar Howard said. "He indicated he was just a passenger in the car. He had no idea what was going to transpire at the time. He was shocked and surprised."Following the funeral service Sunday afternoon several of Gadau's classmates went back to where he died to pay their respects. Like his parents, they're still struggling to accept that two of their own could be involved in his death."I couldn't be more disappointed," said Malik Dupree. "How could someone do this to a friend, a classmate?""I don't believe they knew it was Max," Patricia Gadau said. "I don't believe that. One of them was a former teammate on the swim team. They've both been to my house. I think they're crushed."Skokie Police were not available to comment on the investigation Sunday, but have scheduled a press conference for Monday, following the bond hearing for the fourth and final suspect of those who have so far been charged.