Answer:
I would continue to follow classroom routines and apply different strategies to lessen classroom disruptions. First, I would buy or make a poster of a child raising his hand to remind students of the expected behaivour and order during the classes. I'd make sure it has some rules, like raising one's hand before asking or answering something, to remain silent when someone else is talking, etc, whilst reminding them some rules for the class: Be respectful, be kind, be ready to learn.
In addition, I would remind all students that their names are written on three popsicle sticks, and that they have to wait for a fair chance to participate. If the visual posters and popsicle sticks are not effective, then I would have the student sit down with only one partner instead of group work. This would reduce the student's distractions because it's one on one work. His or her partner would have higher grades so that she or he is able to help the special student. After any incident or issue I'd have one on one meetings with him to talk.
If all of this does not work I'd start collecting information and anecdotal notes to talk to his or her parents to find out the causes of this behaivour.