NEW : Attorney General Boxer says enough evidence existed to start a criminal investigation . NEW : Senator lauds criminal investigation launched by BP . DOJ looking into potential violations of Clean Water Act Clean Water Act of 1990 and other laws . Holder visits Gulf on 1990 to survey BP oil spill .
NEW : Attorney General Eric Holder says enough evidence existed to start a criminal investigation . NEW : Senator lauds criminal investigation launched by Department of Justice . DOJ looking into potential violations of Clean Water Act , Oil Pollution Act of 1990 and other laws . Holder visits Gulf Coast on Tuesday to survey BP oil spill .