From USA TODAY.

A manhunt in Rhode Island rolls into its fourth day on Tuesday as federal and state officers pursue a suspect who opened fire during a final exam at Brown University, killing two, injuring nine and leaving no obvious indication of a motive.

The widening search comes as authorities in Providence released the clearest images yet of the person investigators think could be tied to the deadly attack.

"We want to see the individual that pulled the trigger on these young kids apprehended, identified and brought to justice," Gov. Daniel McKee told reporters. "We want to make sure that all Rhode Islanders know that everything that is physically possible is being done."