SPRINGFIELD — Ten years after the Illinois Supreme Court overturned a man’s murder conviction, it is deciding whether he can sue police officers and the city where the crime took place for the role they played in his prosecution.Alan Beaman spent 13 years in prison for the murder of his ex-girlfriend, Jennifer Lockmiller. But in 2008, the Illinois Supreme Court overturned the conviction saying that McLean County prosecutors and Normal police improperly withheld exculpatory evidence from the defense. Beaman sued …