Surely these children are not victims, but look closer, there are signs. These are usually the children of sexual abuse of younger children. These scars stay in the mind - sometimes forever. Clean up your own doorstep first and look around you. For instance - do you like to be ignored.
Bad behavior is usually a desire for attention.
Ignoring is NOT EASY to do, but this lack of attention takes away the very audience they are seeking. 15 minutes to a child is a lifetime - one program is an eternity in addition long suspensions only build resentment. The child forgets the original wrong doing, which undermines the lesson to be learned. Keep the suspension short - BUT stick to it. Artistic creations on the wall, let the child wash the wall.